Is it morally wrong....

foxgloves

I don't think you're doing anything morally wrong at all. Charity shops have their own pricing policies and charge what they think they can get for the item. While some of them use volunteers who know what to look out for in terms of things that might fetch more on ebay or in a specialist sale, obviously there are going to be several occasions when bits & pieces that are collectible just get put out on sale in the shop. i.e my partner got a Viz annual for 1-50 that he'd seen in a second hand bookshop for about £12. I think that if you buy the item from the charity shop for the price they are asking for it, it then becomes your item to do what you wish with, and that includes reselling it should you decide that's what you want to do.

Frozenace

I think it's a fair deal. The charity shop gets to shift their stuff, you sponsor the charity and then make some money from the risk you take to sell it.

timbstoke

Sounds totally fair to me. If it gives you an uneasy feeling, donate 10% of the sale price to charity. You can even advertise the fact that you do this in your auctions :-)

pinkteapot

I don't think it's wrong unless you try to haggle a discount in the charity shop.