Hi,
I was in the same situation 3 month ago.
After messing around with several cheap RTL2832 I wanted a "better" device, capable of RX/TX.
I looked at all the options, including LimeSDR, HackRF, etc.
My conclusions:
1) The cheapest purchase is the PlutSDR from Analog Devices:
http://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/adalm-pluto.html#eb-overviewIt costs under 100 US$, does RX/TX in full duplex, is compatible to Gnu Radio and sdrsharp. Frequency range is only 325MHz to 3.8GHz, but COULD be hacked to 70MHz to 6GHz. "COULD", because of the major drawback of this device: it is totally out of stock! I placed my order end of September 2017 and Mouser gives me a backorder date of February, 5th 2018. The hack was possible, because you could tell the firmware that the device has a AD9364 instead of a AD9363. It seems that the AD9363 can perform in the extended frequency range, but possibly not fully within specs. The question is if the new batches can be hacked and/or if the AD9363 used will behave like the AD9364. It is thought that early batches might have been fitted with the AD9364 for some reason. I am eager to find out, when my device arrives.
Oh, it also has 12bit ADC vs 8bit on the HackRF.
2) HackRF: "original" or "chinese clone"?
Looking at eBay, it seems tempting to go for the chinese ones, as the hardware is indeed open source: the chinese sellers are efectivily not selling a clone. They just followed the open source specs. However, I have read that those devices may have inferior quality due to cloned/inferior components used. Also, when doing the maths and considering shipping, shipping time and customs, the deal is not THAT attractive anymore.
I just bought mine from Amazon UK and had the device in my hands after 3-4 days.
The HackRF is great. Having a bandwidth of 20MHz instead of the 2MHz of the RTL23832 is by itself worth the money. Being able to TX, as well, is simply amazing. For instance, I did the following tests:
a) Record the whole FM radio band (88MHz - 108MHz). I could then replay it at a different frequency, i.e. 174Mhz-184MHz) and receive individual radio stations with my Uniden scanner.
b) I recorded a analog CATV channel (actually two, which were within the selected frequency range) and again, could TX it at what ever frequency I wanted and tune a field meter to watch the broadcast.
c) I recorded the different buttons of my home alarm remote control, only to find out that it doesn't use rolling keys...

Epic fail! Now I can activate/deactivate my home alarm using my laptop. If I wanted, I could leave the HackRF connected to my home PC and activate/deactivate the alarm over the internet.
There are many more things you can do and my three examples are just the tip of the ice berg. Learning GNU Radio is not so easy: the logic is easily understood, but understanding how to use all the modules takes a lot of time, not to mention programming your own (I am not even close to this level).
Having only half duplex is actually not that much of a big deal, as you can use a separate RTL2832 for RX (within its frequency range), if you really need full duplex.
3) LimeSDR
Great device, but it comes with two issues:
a) Bigger price tag than the HackRF
b) Not so easy to purchase: where do you buy it? On their website only?
c) No case included: I strongly recommend to NOT use these devices without a case. When dealing with cables, connectors, antennas, you WILL eventually have them touch the PCB and cause a short... I speak of self experience...

There are other devices and the prices go up according to specs. At the end you are looking at products from Signal Hound and wondering if you should join the TEA - Test Equipment Addicts...
Have fun!
Regards,
Vitor