$49.99 was all it took for a group of investors to buy the videogame maker Harmonix, makers of the popular, but perhaps not as popular as they used to be, Rock Band series of games, off of Viacom. There was one small catch: the investors had to also take on all the debts and obligations that came with Harmonix. Stuff like music licensing, contracts, warehouses full of unsold game equipment. All told it probably means a 150 million burden. Still pretty cheap for a company like Harmonix. The question now is whether the whole plastic instrument, playing along to Guns N' Roses, colorful lights scrolling by video game category is here to stay or just a fad.