First of all, with the limited amount of snake keeping experience you have, Boelen's are way out of the question. Bad suggestion IMHO.
White lips are also too high strung for your experience as well.
While a BHP is nice too, I think it is probably out of your price range.

If you are looking at pythons, I would suggest womas, carpets, bredli's, bloods, or Macklot's.

Coastal carpets are the largest of the Morelia complex. They can grow to 10'. With morphs such as the tigers, jags, and soon to be caramels on the market, there is lots of possibilites. I suggest a cage of 4' x 2' x 18"H for an adult.
Jungles are a bit smaller and tend to require more of an arboreal cage although this is not necessary. If you look around and spend the time searching for a quality one, you will not be disappointed.
Irian Jaya's (IJ's) tend to grow to 5 1/2' - 6' and also tend to be arboreal.
Diamonds can also be great captives but again, probably out of you price range unless you are looking for a mixed species carpet.

Hope this helps.