This really is a very touchy subject in the reptile world. You are going to find that there are a lot of different opinions on the topic.
Here are the terms from my web site: http://ballpythonbreeder.com/terms-etc/terms-of-sale/.
One of the biggest sticking points you are going to find is whether or not animal health is guaranteed for any length of time AFTER the sale. That really is the toughest part of the live animal business. Some reptile breeders offer "30-day guarantees" or something similar. Most, however, do not. I am guaranteed to have detractors for it but I am one of the latter. I, like most breeders, guarantee live and healthy arrival. I do not guarantee that the animal will thrive under a buyer's care. Once a healthy animal is in the care of its new owner it must become their responsibility. This is true because the seller has no way to to account for the care the animal is given past the point of sale/delivery. As a breeder I only offer animals for sale after they are well established and obviously thriving. Fickle feeder and slow-starting animals are held back until they come around. Unfortunately, not all breeders do it this way. Caveat emptor. This is part of the reason why people are going to tell you to only buy from people you trust or people who have a good reputation.
Sometimes people say that a reputable reptile breeder should provide guarantees similar to those provided by dog breeders. I suggest that dogs are much more tolerant of (though certainly not impervious to) inappropriate environments than reptiles. Snakes kept in sub-optimal conditions will deteriorate very quickly. Dogs do great in a 68 degree (F) room while snakes do not. This applies not only to things like respiratory infections but also to more subtle issues like cage size. A ball python who starts his life in the safe confines of a 6 quart Sterilite tub (which baby ball pythons "love") is likely to be freaked out to the point of not feeding when suddenly placed in the massive real estate provided by a 20-long aquarium. This illustrates the importance of buying from a breeder/seller who will act as a source of advice both before and after the sale.
I invite everyone to also consider the "guarantee" speech that Chris Farley's character gives in the movie Tommy Boy. In addition to being hilarious, it's also filled with truth. It is plausible that a reptile seller will offer a long-term guarantee on an animal in order to give you a warm and fuzzy feeling and complete the sale. But what happens if you need to take them up on their guarantee? Are they really going to be able to give you a refund or a replacement snake? Consider it. Living hand-to-mouth is not uncommon, especially for snake-rich, cash-poor snake breeders. As soon as you give the breeder $1,000 for your new snake you can rest assured that the money will be spent. If, a month later, the snake dies and you expect to get your money back you may find that the seller is not able to back up their so-called guarantee.
The reptile industry contains an amazingly diverse array of characters. Some of the coolest people I have ever met are here ...and so are some of the worst. Do your homework before you buy.
Cheers,