"One thing I *do not* like about mouser is that they don't give you a real estimate of your shipping before you check out. They add the shipping charges when they bill your CC - you never really know what it's going to be. After a while you start to get a feel for what an order will cost in shipping - but there can be some real surprises."
I got really tired of this too. I'd place an order with Mouser and they'd bill my CC with the total + shipping estimate. Then they'd revise the shipping charge from the estimate to the real cost (sometimes up, sometimes down) and bill my CC again. The original charge would then be cancelled, but this might take 4 or 5 days if I placed my order at the end of the week.
I'm not sure if it's a new option, or just that I never saw it before, but recently I noticed that there is now a USPS shipping option at Mouser. I've placed a few small (< $50) orders using this option, and I've been pleasantly surprised. Not only is the shipping cost lower than UPS or FedEx, but in all 3 cases I received my order a day earlier than I expected, and my card has not been charged multiple times to account for discrepancies between estimated and real shipping cost. For large orders, this may not be optimal (if you can get free upgraded UPS/FedEx shipping by hitting some threshold, that might be better), but for small orders it's great!