What snake should I get?

[craigafrechette]

First off, welcome to the forum!!

Right off the bat, my best advice is this: don't buy an animal based on having a 40 gallon tank on hand. That enclosure will likely be too big for any juvenile animal regardless of species. So you'll need something else to start with anyway.

Not to rain on your parade, but proper equipment alone will put a serious dent in your budget. You need heating equipment, which it sounds like you've partially picked out, but only mentiononed one thing out of several. You'll likely need an under tank heater, a heat lamp and bulb or CHE, and a THERMOSTAT (VERY IMPORTANT). That equipment alone chews up most of your budget if you go with entry level equipment, or you'll have to save up more for good equipment. Not to mention hides, substrate, water bowl, etc...etc...etc...

Plus, it's very important to have a food source lined up. Are you feeding F/T or live? Do you have a reliable source for live prey? Do you have freezer space for frozen prey? All things to think about and be included in your budget.
What about money for a vet vist? Emergencies happen and will often cost a few hundred bucks out of the blue.

My advice: save some money over the next bunch of months. Do some research and find a species that you want. By the time you've saved up enough money you'll be more knowledgeable and will be in a better position to bring your new pet home. If you can go to a reptile expo in that time you'll be able to see & handle different species.
Take your time with your decision, a snake is a living, breathing, 20+ year commitment.