How Long to Verify Payment? I wish to allow people to purchase items at my shop using bitcoin.  I've heard however that blocks take 10 minutes on average to process and transactions may not even be processed in the next block if the transaction fee isn't high enough.

So does this mean that my customers will need to wait at least 10 minutes before I can verify they have made a payment and I can allow them to take their item?
To put it simply, it depends on the value of the transaction. There's little incentive for someone to try ripping you off with a low value transaction, but there is a strong incentive to do so with a high value one.

This has been raised before, but the answer that I found easiest to understand is quite old: https://bitcoin.stackexchange.com/a/832/516

Note that waiting for 1 confirmation isn't a wait of "at least 10 minutes", as half the time it will be faster than 10 minutes. For high value transactions more confirmations may be prudent.

There is good info here too: https://en.bitcoin.it/wiki/Confirmation