Best and certainly cheapest option would be the Behringer SF300 Super Fuzz, which is a shade north of twenty quid new, or about fifteen quid used (and there are a lot of them about). Like many Behringer pedals, it's essentially a copy of a Boss pedal, in this case their FZ2 Hyper Fuzz, which being discontinued, is hard to find in good nick for less than three hundred quid. The Boss FZ2 is sort of a copy of the Univox Super Fuzz, and an original one of those would be hard to find in good nick for much less than a grand. So, for the price of a round of drinks in a pub, you can get that classic Hendrix Univox Fuzz and the Big Muff sound as well as more subtle overdrive and level increases with the Behringer SF300 Super Fuzz. Thus you can get more modern tones such as Chilli Peppers, Nirvana, Smashing Pumpkins etc as well as that Sixties and Seventies stuff by changine the modes and tweaking the control knobs.
A lot of people get hung up on Behringer pedals being housed in ABS rather than metal cases, but don't let that put you off, ABS is very tough; you'd have to be a right lead-footed clumsy git to ever break a Behringer pedal case (and even if you could manage to do so, you've broken a twenty quid pedal), which is why I'm happy to have four of the nine pedals on my board be Behringer ones, because they are decent, reliable and as noted, most of them are basically knock offs of Boss pedal circuits with a few additional whistles and bells added, but for considerably less dosh.
Although the sounds out of the SF300 are good and very versatile, it does have one slight downside compared to the Boss Hyper Fuzz, and that's the control knobs, which are a tad smaller than those on the Boss and a bit more closely grouped together, but they kind of had to do that becuse the SF300 has an additional three-position mode select switch which gives you a choice of Fuzz 1, Fuzz 2 and Boost, making it a bit more versatile than the Boss. The Boost means you can sort of use it as an overdrive-ish type of pedal as well, so it can even be a bit Klon-ish. However, be aware that the size of the knobs makes it perhaps less than ideal in a gig situation for quick changes on the fly on a dark stage mid-song, but if you are happy to set and forget it for each tune and either kick it on or off as needed, it's not really a major issue, and for 'bedroom' playing or home studio use, this is a non-issue. So for twenty-odd quid, you really can't go wrong with something offering you all those options in one pedal.