I've ordered live coral online. Probably in between fish and plants as far as sensitivity goes. Close to fish. It went very very smooth i was really pleased. But you must take into account where you buy from and how its being shipped.
Living in a rural area do you get good service from the Post Office, UPS, and FedEX? In most cases vendors online will use UPS and FedEx overnight to ship livestock (plants might be different because they can live longer?) or use USPS if you are really close. Just might want to think about their service to your area before you jump in.
Be sure to maximize your order to make it worth your time. Shipping sucks, everyone raises their prices now because the carriers raised prices to account for gas. So don't order like 1 fish and pay $50 shipping. If possible (smaller vendors usually) Get in contact with the seller beforehand and talk to them, just general questions maybe about their setup, their water, etc so you know where the fish is coming from. Ask for additional pictures if you can.
What kinds of fish are you looking for?