ill tell you right now. Whatever custom rsps you're going to be buying is either going to be:
1. a free download from rune-server
2. a leak / leech
3. a server that has its customs vomited and slurped back up from the past 10-20 other leeches.
you will not be buying anything truly worth while IMO and should rather invest your time learning / buying your own customs which ACTUALLY make a custom server fun. anyways that's just what I think, best of luck finding someone!