Hello Matt, and to BP.net...

How big is the BP you are looking at getting? If you are getting anything smaller than an adult then a 3X2 is going to be way too big and possibly cause you some problems with your snake eating. If you know you want to have a 3X2 as the final, permanent enclosure, then I would look at using a simple tub set-up or a 20 gal. Long screen top tank until your snake is big enough (at least 36-38 inches). You mentioned that you need something that locks. Most glass tanks with sliding lids have tabs for pad locks and there are ways to drill holes in tubs to lock them down with locks.
I don't know if Reptile Basics offers locking latches. The best thing to do is call or e-mail Rich and ask him. If they don't, you can look at some of the other cage manufacturers and see if they do...

http://www.boamaster.com/

http://www.animalplastics.com/

http://www.sentecreptilecages.com/

http://www.boaphileplastics.com/

http://www.visionproducts.us/htm7/cages.html