If you are just interested in the software side of things, you don't need any hardware. You can just create a "transmitter" in Matlab that takes in your data, d

If you are just interested in the software side of things, you don't need any hardware. You can just create a "transmitter" in Matlab that takes in your data, does the signal processing to make the blob you would transmit over RF, and then saves it in a .wav file. Then you could write the "receiver" in Matlab that reverses what you did in the transmitter. This would allow you to get started without buying hardware. Also, you don't necessarily need to use Matlab. Matlab is just what I used when I did this sort of thing in a lab in college.