Mostly wheels, seats, pedal mechanisms, bearings, and cables for 26” frames. Others and a couple of different sizes once I manage to repair the most necessary ones as time permits.
I would search Niagara cycle, as they seem to be about the cheapest, though slow, and good customer support does seem to be lacking.
See 26'' tires and choose size, then sort by price: low to high, and you may see such as this one for under 10.00. S+H is usualy 5.00. And no, i do not work for them.