Seems VERY steep to me! To be honest, you could get a pretty good job at home with a rattle can IMO as the arches are curved, meaning that defects are not as easily noticed. If you take your time, I reckon you could get a great result at a fraction of the price - and if you mess up, buying a single new arch is £5.
Give it a shot and if you dont like your results, you'll only be a few tenners out of pocket. =)
True, I guess I'll order a set of 4 and try it, if I mess it up then I'll just use the ones it came with for now, and maybe get them done professionally later.
Yeah, if you do one and mess it up, you can just replace that individual arch very cheaply =)