That was so fast!, how often do you have to feed it?
The Green Tree Python, when young you feed them once a week and as adults every 10-14 days, really depends on how active they have been and you can tell really, they normally become a lot more active and they also start Caudal luring (basically wiggling their tail like a worm or grub moving about), they do that to attract prey like birds, bats, rodents, frogs and other prey to come close enough to inspect the "worm/grub" and of course get caught and eaten by the python, there are a few snakes that do this in nature and some venomous types to do it.
Caudal luring:-
They are cheap to feed snakes that only eat mice and rats, when you get to the larger snakes and giant snakes that eat rabbits it can get a little expensive as my Burmese Python eats 2 jumbo rabbits every 2-3 weeks and sometimes even 3 rabbits at £10-£12.50 each so she costs me in feed like £35 a month but again she is 18 feet and a giant snake and not one that should be kept as a pet by anyone that doesn't understand snakes, she has the potential to kill an adult and even at 11-12 feet. Thankfully mine is a gentle giant and not once as an adult struck or bitten me.
A typical python or boa that gets to say no bigger than 6-7 foot will cost as an adult if you feed them once a week as some still need once a week £15 a month and if fed every 2 weeks as some require £7.50 a month. When young they will cost you about £6-7 a month on a once a week feed and when very young about £3-£5 a month.
They are cheaper pets than say a cat or dog to feed by a large margin. My Ragdoll cat costs me like £2 a day in feed so £60 a month.
The other great thing about reptiles snakes in particular is they are easy maintenance not like you have to feed them, water them and change their litter tray or walk them everyday. it is basically spot cleaning when they poop or pee and that happens like once a week for some snakes and up to over a month or more for some snakes. So basically can be a once a month clean up that takes 2 minutes all you do is grab a tissue and pick up the mess in that area and some of the bedding and toss it down the toilet.