The Buzz is a great mod, but at least the original version is not as easy to use as the Ego Booster with it's voltage adjustment dial. [If the Infinity had been better manufactured, it could have given the Booster a run for its money.] Also the Ego Boostered eGo is the most slender VV device in the world.
If someone doesn't already have an eGo, the Ego Booster may not be the least expensive way to go VV ... although the total cost ($100 with a $40 eGo from Libery-Flights) is cheaper than most, especially the ProVari. But for a current eGo user, sixty bucks is the most cost-effective way to get tubular VV. [If you like cheap plastic boxes, you can get one of those for somewhat less.]