I'm fairly certain you get billed before your order goes into production, which probably takes a day or two. Since SP is so good about taking supplements back if the horse doesn't like them, or if the horse unexpectedly passes away and doesn't need the supplements, I'm not sure why people would be upset by this. If I order a custom piece of tack or equipment, I'd expect to pay for it, then it would be produced, then it would be shipped.
For the record, I'm not a SP-only type of girl; I have a Dover store just two miles from my house, along with a few local tack stores in the area, and one consignment place. I shop at all of them and whomever has the best deal/customer service gets my $$.