I'm going to answer this but I have to say that I don't have a boa yet, but I do know quite a bit about them (theory wise).
I also have 4 cornsnakes. I love my corns, but I definitely would recommend getting a colombian instead of a corn. If you like the idea of having a big snake then a boa is for you. Some corns can get big, but nothing like a boa.
If you want a bigger snake (than a corn) but not too big, you are right to get a male boa. They tend to stay smaller than the females.
Stay away from the Surinam and the Peruvian boas. They are known to be much less forgiving regarding husbandry errors.
The 65 tank will be fine for your snake for a while, but most people say you need at least a 4'x2'x2' cage and sometimes even a 6' long cage. Also being that it is a glass cage it will be hard to maintain heat and the correct humidity levels.
As far as prices goes, sounds about right, but if you can find a local breeder instead of pet store, it will probably be cheaper and healthier.
Boas need higher temps than corns do, but I'll leave that up for someone else to answer.
As far as length, that too is something I'm not too sure about so I'll give a guess of about an average 5' (for columbian) and average 8' (for the peruvian and surinam). Weights...I have no clue.
As far as time goes, I'd say minimum of 1 hr each week, but 2-3 hrs. is probably closer to normal. Of course this is going by my corn snakes and not boas. From what I've heard, boas are actually less demanding because they poop less often than corns, so you need to clean up less often.
I think snakes are the best pets because of how un-demanding they are. You don't have to spend time with them if you are busy, and as long as they are fed, warm, and in a clean environment they will thrive for you.
If I had more room and money I'd have a ton more snakes.
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alstiver@hotmail.com
Currently own:
1.0 '01 Hypo snow cornsnake (Tesla Coil)
0.1 '02 Ghost (pastel) cornsnake (Banshee)
1.1 '02 Bloodred cornsnakes (Desi and Luci Too)
0.0.3 Goldfish (Kabuki, Isamu, and Yuki)
1.0 '99 American Eskimo x ? mutt (Rusty)
Soon to be added:
1.0 '04 Type II Anery Nicaraguan boa
0.1 '03 or '04 Hypo Nicaraguan boa