Best place to purchase reptile supples?

I have a juvenile leopard gecko and a juvevile iguana. I am wondering where the best place is to purchase a habitat for them that will be big enough for each of them to live in when they get grown. I have seen the ones in the pet stores for my gecko that has the swing open door and was wondering if something like that is better than just a 10 gallon tank and if so, what size should I get for him. As far as the iguana, I have a 55 gallon tank for him right now, but I know that he will be out growing it sooner than later and I am looking for a great place to purchase a large enough tank for him that will work for him when he is grown. How big should I get it? The pet stores don't really carry the iguana cages big enough for an adult iguana here and so I am looking for one online and I don't want to spend money on one that he can only use for a while. When he comes out of his 55 gallon tank, I would like to put him in his permanent habitat and not have to keep buying cages for him. Please answer only if you are serious and I would prefer answers from experienced reptile owners. Thank you