Man I got into this stuff at just the right time lmao (and yes I'm a Game Grumps fan)
I'll be visiting an audio electronics store in a week or two to see if I can find a true real deal cassette recorder. Until then, I found this cheap multipurpose boom box at Wal-Mart. Finally, a tape player that's new and works even if it isn't top quality.
Using FM transmission, I can bypass the FM recording limitation and put whatever I want on the tape. As heard right here.
(Edit: I'm an idiot, it is possible to record line in directly, I just wasn't doing it right)