I'm a charity shop volunteer and from what Daan says it sounds very much like the same chain.
Not hijacking your thread Daan but thought I'd back up what you were saying.
We do get to buy things we spot, but never make that pricing decision ourselves. We always ask the manager, or if she's not in, the most experienced volunteer to price anything we want to buy. My absolutely best things were a BNWT Hobbs woollen coat and a new pair of Doc Marten boots. Love them both and wear them to death every winter.
Shoplifting in our store is a real issue. We have a glass counter/cabinet thing where we keep all the valuable stuff, or it's sold through the online shop. First job in the morning is always to tidy the rails, and every shift I find swaps - someone's come in wearing a manky old coat/top/whatever, taken one of ours off the rails to try on, walked out wearing it and put their manky old item on the hangar. We also have label switchers who take a label for £10 off an expensive vase and replace it with a 99p label from something else - a lot of this happens when the volunteer with special needs is on the till which is absolutely despicable.
Our store doesn't sell electricals - but one along the road does. Anything we get which we think we can sell we'll take to them rather than binning it. All unsellable textiles and books get recycled too. A lot of the junk we do have to bin though, it never ceases to amaze me what people hand in - things like chipped or broken crockery, DVD boxes without any DVDs in them - how are we meant to sell that??
On the pricing thing - yes we do have a pricing guide but that relies on a volunteer recognising that "Atmosphere" is actually Primark and that it's therefore cheaper than Reiss or Hobbs. Mistakes happen. Our chain gets weekly performance figures which the manager can compare with other branches and last year. Our aim is to make money - it's in nobody's interest to have stock sitting around for weeks as it's overpriced. So the mantra is always "price to sell" and if we find something overpriced we'll whip the ticket off and put something more realistic on.