Why do you need Tx for an IMSI catcher? Also, a USB TV tuner won’t work for the receiving side either. You’ll need to step up into an actual proper SDR for that. Still easily sub $500, but sub $100 is a bit too far a stretch.
A $12 RTL-SDR USB stick will 100% work for most GSM rx (won't hit the 1900+MHz bands without a downconverter, but that's why you want tx - you'll use it to force the phone onto the 800-900MHz bands anyway, the top half of the 915MHz ISM band in the US if you have a HAM licence and are trying to not break _too_ many laws at once).
Gives a good overview of why you need tx to capture an IMSI - without forcing a handset into transmitting non-encrypted, you only get the TMSI (unless you can crack the crypto - and why bother, when a base station can instruct a handset to just not encrypt anything?)
