I went to our local car upholstery shop and interviewed the guy for some tips on building a higher seat core for a dirtbike. I needed seatcovers fot at least three bikes anyway, so I bought the stuff there. The material is obiously better quality than stock seat covers. OK it is plain black, so there are no cool decals and logos on it, but I got enough for 4 seat covers for 20 Euro. That is something between 15 and 17 US Dollar I think.
Installation is a half hour job maximum, when you have an electric staple gun.