Not sure if this is legit:
https://www.blackminerscam.com/blackminer-f1-scam/
Closest your going to get to$100 is a f1 mini
I'm going to have a go with the F1 mini since it's the most affordable FPGA miner available on the market. I don't mind if it "steals" hashpower, as long as I'm able to learn how FPGA mining works. I want it for learning/experimental purposes, than making profit. I'm not surprised to see some PoW algorithms being taken over by ASICs, since there's really no such thing as "ASIC resistance". Developers need to adapt PoW algorithms over time, in order to maintain such resistance. The beauty of FPGA miners is that you can easily adapt to another algorithm by simply downloading a bitstream or programming it by yourself. ASICs on the other hand, are disposable since they're fixed to an specific hashing algorithm. That's why FPGAs have brought my attention lately.
Nonetheless, I appreciate your recommendation for getting started with a cheap FPGA miner for learning purposes. I'll try doing solo mining with it, to see what results I'll get in the short term. I'm planning to upgrade to a much more powerful FPGA miner once I learn how everything works. My next mining setup will consist of FPGAs and GPUs, instead of ASICs. I'll be a fun and exciting journey as I mine altcoins for profit.