Hackaday article Spoofing Cell Networks with a USB to VGA Adapter tells that at OsmoDevCon [Steve Markgraf] released osmo-fl2k, a tool which allows transmit-only SDR through cheap USB 3.0 to VGA adapters based on the Fresco Logic FL2000 chip. Available through the usual overseas suppliers for as little has $5 USD. The claim is that these devices can be used unmodified to transmit low-power FM, DAB, DVB-T, GSM, UMTS and GPS signals. A GitHub repository has been set up which includes examples. For a few bucks, you’ll be able to get a device that can transmit may radio signals.
This reminds me of Analog and Digital TV (DVB-T) Signal Generation using VGA card idea I mentioned at Interesting VGA hacks posting.