Should charity shops provide bargains?

Saw a snippet of Mary Queen of Charity Shops last night. I usually quite like her programmes, but this one seemed incredibly patronising - getting 82 year old women to practice selling vibrators; Mary prancing about in patent leather boots whilst informing volunteers that the boots are: "PATENT. Leather. VERY on season. ON season."

The idea, I think, was to get charity shops to sell designer donations at expensive prices. What then is the point of charity shops?

The best thing about shopping in charity shops is the chance that you might get a real bargain. Recently charity shops in posh parts of London have been pricing things up - you find second-hand Primark tops are more than they would have been originally and horrible frocks priced at £50 just because they are "designer". Makes me want to avoid them entirely. And that can't be good for business.

Actually, have just noticed a thread about a similar subject on the brilliant Cheapness Studies blog.