10-15...ish? some were never finished and some of the first tries left some to be desired. it's fun for me though, like rideable creativity.
harbor freight has their lowest price welder for sale periodicly for under $100. i've never done a complete bike with mine, but i'm getting better i think. the 29er cruiser i posted in the show your cruiser thread i stretched and tacked together at home, but just yesterday i decided finish up the welding at work. i know plenty of people do all the work with them and i'm meaning to get to that point myself eventually.
i wouldn't say i've ever built a burrito. there's a little more to them. i've got an idea in mind for one, but i'd say what i've built are just stretch cruisers.