I don't mean to offend you in any way. I just wanted to get over that before I reply to your question. Owning a retic is a big responsibility, more so than a monitor lizard or a carpet python. A large retic can KILL you. That is not to say that they are evil. It's just that one mistake can cost you your life. In my opinion you should be glad that your parents let you have your other animals. If they feel that they don't want a potentially deadly snake in the house, then you should obey their wishes. Retics can be very docile but you must remember that they still have wild instincts that must be reckoned with. If your carpet python is an agressive feeder, then you know how hard a snake can strike at its food. Imagine a 15 foot snake with this feeding response. If you are going to be caring for a large retic, you should make sure that you have another person that can help you or at least be within hearing distance in the event that you are attacked. I am not trying to make retics seem mean; I'm just telling you the truth.
When it comes to dwarf retics, you should try contacting Bob Clark(www.bobclark.com) or Mike Wilbanks(www.constrictors.com). Remember that although a dwarf retic will initially cost more, you will probably save money on feeding over time. A larger retic will of course eat more than a smaller one. Also, a larger snake will need a larger cage; which translates to more money being spent.
Sorry for the long post............