Where exactly did you see the FPGA sale? It could be some older miner using them and are not selling off the hardware to someone else at a price because its is comparatively useless now.
ASICs are the way to go with any type of mining. I still cant remember of any altcoin that would be profitably mined with FPGA let alone worth recovering the cost of acquiring them and setting up the place, electricity and maintenance.
But I agree with @badbart that future altcoins may have something good for FGPAs running their algo but then again there would be the problem with newer hardware coming up to compete compared to older one being sold.
Yes. ASICs are definitely the way to go for crypto mining. There's no doubt in that. But FPGAs seem to be an interesting venture that could prove to become a viable alternative to GPUs or even CPUs if heavily developed over time. In the meantime, I'll be using an FPGA just to experiment or play with it a little. It could serve as a great learning/educational tool for crypto mining (just like an ASIC would nowadays). I've seen some FPGAs on sale (most of them are used) over at eBay with different price tags (depending on condition, and power). I could just buy one and keep it as a future mining device, in case a new cryptocurrency allows FPGA mining to become great again. But for real crypto mining, ASICs and GPUs are the norm these days.

I also heard that FPGAs are almost their mining any coins developers can make a new bitstream but they actually not sharing it they mostly ask you for another payment or wait for their release.
According to
https://fpga.guide they are making a profit while mining on some known coins I don't if it's true but some people on reddit told me that they can make a better profit on mining with FPGA than GPU because there are developers always release a new bitstream free or for VIP users.
If you are going to buy FPGA I think much better to research first there are some FPGAs not worth it to try.
Interesting. I didn't know about this before. This site seems like a wonderful resource about everything related to FPGA mining. It's a good find. Thank you very much. I believe that FPGAs are much easier to configure than an ASIC itself. Also, FPGAs have a lower barrier of entry than ASICs. Even if ASICs are much more cost-effective than the former, I'd prefer FPGAs because of their "programmability".
Despite this, I believe that ASICs will continue to dominate the crypto industry for a very long time. As long as Bitmain is still out there producing new ASICs every once in a while, FPGAs may never rise to their former glory
