That's a good price. Whether it is any good or not depends on who manufactures that "510." Joye was the first (and considered by many to be the best). Since the Joye 510 has been so popular, there have been many imitators, some of which are pretty good ... others not so much.
Unless you must have a very slender e-cig (just like an analog cigarette), I recommend that you get an eGO-type PV instead. For example, for the same amount of money, you can get a Riva kit (also 2 batts and 2 attys) from Liberty-Flights (using 20% off discount code: ecf). It uses the same atomizer, but the battery is 750 mAh (to the 510's 180 mAh): providing many more puffs per battery charge ... and enabling the use of more powerful ("LR") atomizers and/or greater capacity cartridges.