CALL THAT CHARITY !?!

I recently passed a charity shop in my 'locale' to have a look around and see if i wanted anything.
I actually found a couple of books i wanted and also some other stuff, so i looked at the combined price's of the objects and fucking hell!! i wasn't trying to buy the whole bloody shop, i only wanted a few things but the price was well over £15!
This was an OXFAM shop for gods sake, i wanted to just buy a few things that were second hand and used, not new items, and half of what i wanted was not in the best of condition either, but i had to remind myself that i was in a 'charity' shop, the only 'charity' needed was for me so that i could afford to buy anything, it really was that expensive, i checked.
Not all charity shops sell their stuff at such high prices so why do OXFAM charge so much for everything? the prices are beyond the financial means of those 'poorer' people who are forced to go shopping in charity shops in the first place, so who are they for? the sort of prices they ask is pointless, you can get the same things new for just a little more.
I'm assuming (rightly or wrongly) that they have to charge a lot because the 'administration' costs are so high, or not, who knows.........?