There are tons of MIDI controllers.
Most MIDI controllers are keyboards. If you're looking for a guitar-like controller and you're on a tight budget, your choices are rather limited. A PS3 guitar controller can be adapted for MIDI, but there are better options. Look for the "You Rock Guitar" controller. They're sold new for about $250 US. If you win the lottery, check out the Starr Labs Ztar. You may also be able to find older equipment on the used market. The Yamaha G-10 was a "pro" solution in the 80s. The Casio DG-20 was a bit more toy-ish, but had strings and MIDI output.
Guitar-to-MIDI may be another option but it works differently. It uses a hexaphonic pickup on a real guitar. A converter box translates the detected pitches to MIDI. Your cheapest options here would be to find a Roland GI-10 or Roland GI-20 on the used market. Casio also made the PG-380. It was a real guitar with a built-in converter and MIDI output.
There are percussion controllers, pad controllers, accordion controllers, and all sorts of outlandish things out there!