If you're after a tubescreamer-type pedal, and you don't want to spend too much, you could try the Joyo Ultimate Overdrive, which is a TS clone – I got mine for about £30 – or a Boss SD-1 (which behaves slightly differently, but serves much the same purpose, and lots of places seem to offer a mod that converts it to TS specs). At the cheaper end of the scale, I've also heard good stuff about the DigiTech Bad Monkey, although I've never used one personally.