I googled "shipping fish" and got 992,000 responses- the first few look very informative.
Even a brief scout around Aquabid can show you that the vendors are using heat packs, oxygen, and FedEx etc.
Do you think someone would pay $30 shipping for a $5 dollar fish? The jacks and oscars are a dime a dozen, and I wouldn't think a 12½" pleco is the best fish to learn packing/shipping on.
I'd think a local sale to be your best bet.