I do not have experience but it seems self-contradicting to order online.
$15 fish online compared to $20 in store
$15 + $40 shipping = $65
The only way to get your money's worth is to buy multiple fish at once, which I believe is going against adding fish slowly to your tank. I would think to only buy online if there is a really neat fish that they cannot get locally. And even then do not buy online unless you've ASKED your LFS
to specifically get it for you. (got my candy pistol shrimp this way) granted it is a common shrimp but still.
This is all my opinion and speculation though :P