A burm can hit 10' or more in its first year of life; same deal goes with the anacondas. For example, my two burms have been growing at a rate of about 1" per week, so I'm looking at having two snakes that are at least 6' by the time that these two are a year old in July. You're going to need a minimum of a 6' x 3' x 2' cage for an average-size male burm; a big female will need an even bigger cage. These snakes will outgrow the aquariums that you have in a matter of weeks. You're also going to need someone who's going to be able to help you handle the snake when it gets bigger since these snakes are super strong and can get pretty heavy.
In my opinion, a carpet python is the best choice for you. You'd be good to go with a 3' x 2' x 2' cage for an adult carpet python, and they still get to be a decent-size. You should be able to get a nice one that fits your budget, too, although a jaguar might be out of your price range.
If you absolutely must go big, then get a burmese python that's not just an albino morph (maybe an albino granite or albino green). These are probably the most docile of the giant snakes, so they're your best bet for a first giant.
EDIT: You could also look into half-dwarf burms; they're supposed to stay under 10' as adults.