They're all made from different pieces of wood, so they're all different.
Always try the one you want to buy before you part with your cash if you can.
agreed (and with wez too). Generally, the higher the price, the better QC *should* be (though it's not always the case...).
i guess it also comes down to how much you're saving. If it's a minuscule percentage (say a saving of £20 on a £1000 guitar) I'd pay the extra so I could try the one I was thinking of buying.
But if the guitar was, say, £200 on the internet and £400 in your local shop, it might be worth the risk, especially if there's a decent return policy.
That's how i generally work anyway.
EDIT: also, it's worth mentioning the online price you've found to your local shop. It might not work, but it's worth a try.