Been using them for years, and they work absolutely great. Specially in places that have power, but you'd have to rip out metal/walls for network cable (like boats RV's and planes). Unfortunatly, they usually only go to around 14Mb (faster than B but slower than G), and many many people want a way bigger number (like 108 Mb), so they can wrongly say that their 4Mb Cable or 2 Mb DSL/sat is faster than anyone elses and runs at 54/108 etc...
Why spend 50 or 60 bucks, when you can run new cat 5/6 wires in walls for hundreds/thousands? This is the USA.. It's imperitive that you waste thousands of dollars on something you don't need but is cheap/easy/works great in most situations.. our economy depends on people spending large amounts of money they don't need to. You'd be a commie if you didn't spend thousands more than you have too, and keep our economy growing.