interesting i saw those on ebay ,they do suposedly 70 KH/s for 59.99 or 5 of those for 300 can do 350 KH/s but 1 grid seed alone can do that for less so those are kinda of rip off if they ever got cheaper i guess it would be ok due to the low power consumption but they would have to be like half the price they currently are asking for.
The 60 KH/s (or 70 KH/s or whatever) USB sticks are not cost effective and are not supposed to be. They are more like toys. Just to clarify, they are all gridseed devices, at least I'm not aware of anybody else making them. The USB stick has one ASIC chip in it, the larger device has 5 of the same chips, hence 5 times the performance. The larger device also connects via USB but requires a separate power supply. They were selling for $250-300 not long ago, so it's a race to the bottom now.