I would advise getting a book that's gives details on rabbit health and care, but here are some good tips on where to get a bunny and how to make sure that the one you are getting is healthy. Personally I get my animals from shelters because otherwise those animals might not get a good home, but I don't think there are as many rabbits in shelters as say cats or dogs. Otherwise I would buy from local, smaller pet store, not a large well know chain like Pet Co. Smaller shops tend to take somewhat better care of their animals, and the animals get more human contact, so they are more likely to be used to humans already. As for checking the health of a bunny that you want to buy, here are some helpful tips:
1. If the bunny is not asleep or tired, it will probably be alert when you are near it and it knows you are there. It should be twitching its nose almost constantly, and unless it is relatively docile, it will widen its eyes when it notices your presence. Most good pet stores will let you handle their animals if you ask, but be sure to ask how sensitive the animal is, because if it is particularly scared of people or does not like being touched in a certain place, it might bight you because it is afraid you will hurt it. This does not mean the animal is "mean", it just means you will have to build a bond of trust with it until it isn't scared of you. When you touch it, it should react, if it does not or seems not to really even notice, then it may be sick.
2. While you are holding it, check the insides of its ears for spotted discoloration. This could mean the bunny has ear mites.
3. Ask someone who works there if the bunny will let you open his mouth. If yes, open it and check that is buck teeth are not growing too far down, because if they touch the roof of his mouth it can cause an infection.
4. Run your fingers through the fur to see if it is thick, glossy, and healthy. Do not be alarmed if the hair comes out in tufts, this probably just means that he's shedding.
IF YOU NOTICE ANY OF THESE PROBLEMS, YOU SHOULD TELL SOMEONE WHO WORKS AT THE PET STORE SO THAT THE BUNNY CAN RECEIVE TREATMENT FOR ITS PROBLEM! Otherwise, the bunny might get really sick before anyone notices.
5. This isn't exactly a health concern, it is a good idea before buying a rabbit to either buy a good pet care book that also tells you about different rabbit breeds, or look at internet sights like wikipedia. There you can look at different breeds to choose the one that's best for you, and look at the supplies that you need so you can be prepared for the bunnys arrival. I hope you find a great pet!
An animal lover ;)