In reply to jonah_cook:
FWIW the two extra harnesses I have for taking friends or clients climbing who don't have their own harnesses are Petzl Corax. It's one of the best "one size fits most people" harness around.
For scrambling something really basic but massively adjustable like a DMM Alpine, DMM Brenin or similar (as used by lots of outdoor centres) is more than enough but for any proper climbing they are really poor. They are certainly cheaper but not massively so.
If you are willing to compromise on having a massive size range then the venerable Black Diamond Bod or Alpine Bod is a possibility. The wrap around design is especially useful for scrambling or mountaineering where they are easy to put on whilst still wearing hiking boots. However easily the best scrambling and mountaineering harness at the moment is the Blue Ice Choucas, essentially a dyneema version of the Bod design. Probably a bit specialised but it's a great bit of super lightweight kit
I certainly wouldn't be spending £60 each on spare harnesses and if I was, the DMM Renegade wouldn't be one I was actively considering.
My advice would probably be to either search around until you can find a good price on the Corax (IIRC I paid under £40 each) or look around for sale bargains. There is a fairly good chance of finding something with a similar double buckle design heavily reduced at this time of year.
HTH