I've been buying shot this way for years. I just watch the shipping deals offered and buy from who has the best offer at the time. The last two orders I made was from BPI @ 12.99 USPS flat rate. I had to go down to the post office to pick one of them up because they said it was too heavy for the carrier to deliver. The other order was delivered to my door step a few days later.
I've been lucky that everything has worked good for me, but I have a friend who had an empty box delivered because the shot broke the box apart during handling. Luckily the dealer made it right & shipped him another two bags @ no charge, but I'll bet there was some foul language being used wherever it was that had all those #8's rolling around