If you have never tried them before I'd recommend going for one of the cheaper brands like Blu, ProSmoke, or Safe Cig. They all have starter kits for about $60.
If you like them, then you get one of the nicer kits. Check out the e-cig section on this site, they have coupons for almost every brand.
Just make sure you are buying a kit and not a subscription into a monthly refill service, I made that mistake once