Hi Allison,
I'm not sure what your state laws are regarding ally snappers, the best way to find out is to contact fish and wildlife. I know in some states such as California it's actually illegal to own any species of snapper. After you find out that bit of info, make sure that this is the species that you want. Alot of people get them because they think they're cool (which they are), but abandon them once the 'new' wears off or the animal outgrows it's small enclosure. If your serious about this species, buy captive bred and avoid wild caught. These guys have been hit hard by humans and though it may be tempting to buy a large wc animal, this only fuels the fire and contributes to the problem. Sorry if it sounds like I'm nagging (it's not my intention to sound like that) but I do alot of reptile rescues and I've seen way too many people 'dispose' of their pet once they realize that they've made a mistake.
They are truely remarkable animals (one of my favorite species of turtle) but they do get large and can be dangerous if not treated with respect. Best of luck. ~Christy