Plenty of options with varying levels of cost and/or complexity. For example, you could try Matlab’s HDL coder/Sysgen and an FPGA eval platform with eval board transceiver. National Instruments also has a good platform to start with using Labview and the Ettus USRP devices. OpenAirInterface has been developed to work with the USRP devices and has a fairly active community led from Eurecom.

> and an FPGA eval platform with eval board transceiver

Know of any vendors providing these offhand? The Ettus radios are very cool, but sadly a bit out of my price range.

You could try the Xilinx ZC706 with an ADI9361 based FMCOMMS board. The OpenWIFI team has a few configurations listed on their readme that are popular: https://github.com/open-sdr/openwifi. I think these setups will still cost >$1000USD and require considerable effort to get going - I don’t know of a <$1000 SDR setup for 5G development that would be easy to setup and get going with. Curious if anyone knows of one.