Comment by UncleOxidant

You can apparently use the open source yosys/nxtpnr tools with the tang nano 9k, but, unless something has changed recently, nxtpnr doesn't work with the 20K yet. However, I found the Gowin tools to work reasonably well (and definitely way less bloated than the Xilinx & Altera tools.)

At a higher price point but with more capability, Digilent has a one-week 20% sale on their FPGA boards this week. Some good options (Artix 7 and Spartan 7) within spitting distance of $100.