Depends on what you're looking to spend.
For a less expensive, entry-level product that most people tend to upgrade from, the 510 is a great model. Battery life is short on them however, but they push consistent voltage to the atomizer from first to last hit, where as other models can drop off and affect your overall experience.
Almost any supplier has a decent 510 starter kit for around 30-40 bucks, depending on supplier, one of the first things is to see if there's a supported supplier near you, since they're all over the world right now.
If you want another option that quite a few folks are swearing by right now, but is a bit more expensive, there's the eGo or tornado (same thing, different catchname) I believe it's also called the excalibur as well. It's pretty much a remodeled 510 to work better. These tend to run 60-90+ for a starter kit (depending on the kits themselves). They use the same 510 atomizer which is desirable (510's are of the widely regarded opinion of producing much better vapor than say a 901 or similar) but the battery life will be around 6-8 hours per charge, which in the long run, is a much more desirable run time.
If you're an adventurous sort, you can dive headfirst into mod style vaporizers. This, however, is something you'd want to research thoroughly since there's always a positive and a negative to them, and some of them require a longer wait time from order to receive as they're custom built.
My advice, start with an eGo/Tornado kit, you won't have to stress about having extra batteries always, won't necessarily want to buy a passthrough 2 days after getting it either for easier power needs. Or if you choose a 510, look for the mega batteries, they last around 3.5-4 hours, as opposed to the 1.5-2 hours the normal 510 batts do.
Anyways, back on track since I hijack my own paragraphs with rambling cowcrap. The eGo/Tornado/Excalibur/etc is in my opinion, a better choice to start with.. I love my 510, don't get me wrong, but I've already ordered a Chuck to move up to.
