Not sure about the definition of "affordable" (faster always costs more money!), but there's another vendor of diff probes named "Cal Test" that has a model CT3688 at TEquipment rated for 200MHz. It's a 10:1 probe for just about a kilobuck.

More bandwidth than I need and more money than I want to spend, but if you really need 200MHz the price is obviously going to be up there.
This Cal Test unit appears to be a relabel of the Sapphire SI-200 as shown here:
http://www.sapphire.com.tw/si200ds.htm. Looks like there's a lot of relabeling in the diff probe industry... I'm surprised there's enough demand to justify it, diff probes are somewhat specialized. Even Jim Williams (RIP) of Linear (RIP) said most people don't even know what they are!
Pico is another vendor. They have their 10:1 TA045, rated for 200MHz, also right at $1K. Looks like the going rate for bandwidth is $5/MHz. That's even roughly true for Dave's diff probe, 70MHz for ~$350-400 depending on vendor.
I'm finding there is a (pardon the pun) differentiation between diff probes meant for low voltage / small signal work, and those meant for high voltage protection/isolation. The latter have huge voltage divider ratios, some as high as 1000:1. That's lovely but I suspect those are less optimal for small signal work that a probe designed with that in mind. That's why I'm looking for one that has 1:1/1:10 options... you know that one will be designed specifically for small signal work.
In my case I'm trying to measure differential voltages in the tens of millivolts. I don't really need an extra 10:1 division between me and a signal that small. If the price turns out to be too high, I'm also toying with the idea of just building a custom diff probe, perhaps a discrete instrumentation amp with a front end based on something like the LMC6001. That sucker has 100% tested input current of
25 picoamps at room temperature. Its GBW and slew rate are pretty low but if you run a pair as voltage followers and let the downstream device handle differentiation with a gain of 1, you could have a pretty impressive 1:1 diff probe for DC and low AC applications.
Still searching....