Internet radio mostly.
Sometimes friends also interested in music will bring some new stuff by to give a listen to.
Public library on occasion.
I'll do some digging on various internet sites where users post reviews and comments on specific material as well when time permits.
I'll do an occasional raid on budget used vinyl for a couple bucks or less also when I get a chance, but I much prefer a quick rip to music server where I can quickly find and sort through new material as needed.