Alright, correct me if I'm wrong (the experienced snake keepers only), but aren't retics mean little buggers? Not mean like they'll bite your hand off, but mean as in unpredictable (much like burmese). Now I don't work in a petshop, so I may not know anything at all about snakes (although I have kept many for years) but I would say a reticulated python is not a good beginner snake...especially for a 14 year old.
Every aspect of your post and comments screamed irresponsibility. When buying -any- animal whether it be a common goldfish to an extreme exotic ALWAYS know how to take care of it BEFORE buying it (and yes, this is coming from a person who spent over a month researching how to take care of a 2 dollar goldfish...we won't get into how may resources I looked into before I got my first snake). Also, know the laws in your state. If HHMoore says they are illegal in New York I would bet all of my assets on him being correct, not because he once was a part of a petshop, but because he actually knows his stuff.
The reticulated python is one of, if not the, largest python. It will get well beyond 6 ft, and not only will it get beyond 6 ft. but it will be a heavy moody little bugger and one person would be highly advised against trying to handle it by themselves. If you're dead set on keeping this snake realize you will be hand building it's cage, and it will take up a lot of room. You will not be able to feed it mice, you will more than likely have to go up to rabbits. Some time check out frozen feeder sources and you will know how expensive these can be and how many little things can add up to be 10x more than the snake itself (for example my first ball python cost me 25 dollars through a reputable dealer, and the simple set up cost me over a 100).
Please also remember that people in petstores are paid minnimum wage and are there because it's a "job". They don't always know what is best for the animal nor do they always care. The people who are here are here because we want to be-not because we're paid 6 dollars an hour to be. This is a hobby/passion/business/life style for 99.9% of the members here and thus we are more than willing to share our opinions and experience with you-all you need to do is NICELY ask.
I do commend you on getting a third opinion about how to care for your snake. That alone says that you have some desire to properly take care of it.
If you want to get into herps, I would recommend a more docile snake. Milksnakes, cornsnakes, and ball pythons are all pretty good beginner snakes.
Best of luck, and remember that we aren't saying these things because we're ignorant; we say these things because we do care about the wellbeing of animals and the hobby.
~Jenna