2x Agilent N5306A PCIe gen 2 protocol analyzer with x16 options and x16 interposer card, paid ~$3k, current list >$120k
Agilent 1169A 12 GHz diff probe with damaged insulation (cosmetic issue only), paid $400, current list $11k
HP 85645A 25.6 GHz tracking source, failed self test, bad LM317 + shorted cap, paid $1k
HP 83440D 30 GHz O/E converter, missing the label so seller thought it was an 83440C, paid $120
How did you get such amazing deals?
All of that stuff was just getting really lucky on ebay.
The PCIe protocol analyzers are very specialized pieces of equipment. It's not like a DSO or an SA that you can use for all sorts of stuff. A PCIe analyzer connects to a device either with some sort of flying lead probe or with an interposer card. It captures the data on all lanes of the bus in both directions and stores it, then decodes all of the transactions. I have been doing some work with FPGAs and PCI express and I did a quick ebay search to see if there was anything available. As luck would have it, there were actually two different systems available - one 8 lane, and one 16 lane, both with interposer cards. I actually bought both of them, one for myself and one for the lab. The analyzers are specialized equipment, so the list price is high and the resale value is low, and they depreciate like mad. Agilent also makes gen 3 capable analyzers now so they're a generation older. The 16 channel analyzer is two cards at $30k each, plus $20k each for the 16 lane licenses, plus the cabling and interposer card, IIRC. Most people who need one are manufacturers doing PCIe compliance tests, and they would just buy it new from Agilent. It's actually a rather significant PITA to use - the dang thing is network booted and requires a dedicated network card, and the software package installs about 5 or 6 services (FTP, DHCP, etc.). So I have to run it in a VM and then use a USB network card, and everything has to be turned on in the right order. And usually it doesn't come up on the first try and needs to be power cycled. And then the software is rather unstable and has a propensity for crashing. But I did manage to find two different bugs in the Altera PCIe reference design with it. The actual capturing of the PCIe bus is performed with a Virtex 4 FPGA and several GB of DRAM. The analyzer cards and interposer cards actually have a rather interesting stackup - the inner layers are all standard FR4, but the top and bottom layers are some sort of RF substrate - rogers, duroid, or teflon - so the boards are very bright green with white bands around the edges.
The differential probe was just luck. I have had a watch on infiniimax for months, and it popped up along with a differential SMA adapter. The thing had a nasty gash in the outer insulation on the probe cable and it was sold as 'untested'. I figured it would be a good deal if it worked, so I went ahead and placed a reasonable bid. Turns out the gash only affected the outer insulation, the coax and low frequency wiring inside were all fine, so I just taped it up. It works perfectly with my Infiniium 54854 4 GHz DSO. I have not tested it with the DSA91304A that we have in the lab yet. Oh, I also managed to score a set of 4 new in sealed original packaging Agilent custom "BNC" to APC 3.5 mm precision adapters and an infiniium calibration cable for like $150. I paid $10 for the cable, which was mislabled so nobody found it. I only found it because I was browsing the other items of the seller with the adapters.
The tracking source is an interesting story; originally it sold as 'untested, as-is', but listed as 'used' for $3500. And it was a suggested item for something else I was looking at - I didn't even know such a beast existed before I saw it. However, the guy who bought it is a bit of an a$$hole who buys instruments listed as 'used', testes them and gets them calibrated, then sells them for 2x (or more) what he paid or returns them if they don't work, even if the original seller listed them 'as-is'. (if you list anything on ebay that you don't want coming back to you because you didn't test it and it turns out that it does not work completely, 100%, you cannot list it as 'used' on ebay, otherwise some dude will buy it and return it and force you to eat the shipping cost due to the implicit ebay guarantee on used items) So two or three months later, it turns up again, listed as 'parts or not working' for $2k. I contact the seller and ask him to run the self test. It comes back with an ADC vref error. Hmm, sounds like a bad power supply. I manage to talk him in to parting with it for $1k. After I get it, sure enough, +32.5v is reading zip. So I pop over to radioschmuck for an LM317 and replace it, and remove the shorted capacitor that caused the failure. A few weeks later it stopped working again. I traced that one to a failed 1 M ohm resistor in the power supply power good detect circuitry. Again, a trip to radioschmuck for some 1 M ohm resistors later, and it's operational again.
As for the OE converter...I bought a 83440C from a guy on ebay for around $200. A few days later he lists an '83440C' with no label, but it has an adapter of some sort attached to the RF side. Looks like an attenuator or something. However, the actual connector on the device is a different color. The 83440C has a 3.5 mm connector that's good to 26.5 GHz. The 83440D has a 2.4 mm connector that is good to 50 GHz. 3.5mm and 2.4mm are not compatible with each other, they have different threads and different center pin sizes. (FYI, SMA, 3.5mm, and 2.92mm (K) all work together, and 2.4mm and 1.85mm (V) also work together) To highlight this, the 3.5mm connector is gold plated while the 2.4mm connector is silver plated (probably nickel, but I'm not entirely sure). Anyway the connector on the '83440C' is silver, just like all of the 83440D. So I made the guy an offer on it.
I also picked up not one, not two, but THREE old ASIC emulators from ForteLink (now part of Synopsis, so no hope of getting any sort of documentation) that each have 11 large Virtex 4 FPGAs one one gigantic board. For around $2k for the lot.
So, if you want screaming deals, you need to cast the widest net you can (general watches on ebay), be willing sit and wait for a long time, contact sellers and make offers (many of them don't know much about what they're selling), check out everything a seller has listed (you might find something really interesting), and be very observant. Eventually, you will get lucky and get a really good deal on something.