Programmable and/or DPDK-P4 NICs - What to buy to experiment with?

So for the next R&D project, I'd like to toy around with programmable NICs - either FPGA-based or standard NICs I can do some interesting things with for DPDK, P4, etc. I have a lot more research to do here, but is there an easy answer in terms of picking a "well supported" NIC or NICs to do interesting things with in this arena for a small lab? No more than 10Gb