You can buy this dev board to play around with and learn FPGA for $75, and it has extensive documentation and resources to help you
However if you're doing the sort of work which isn't just hobbyist stuff, you're going to spend 1000s on a board. This is the sort of thing commercial developers will be using: https://www.xilinx.com/products/boards-and-kits/ek-v7-vc707-...