techknight said:

Gotta watch out for cheap power supplies though. They tend to go erratic, or throw out noise and unstable voltages. 

In most cases though they are fine, but you do have to watch out fo rthat. 

Click to expand...

The ones I was looking at appear to be based on standard National Semiconductor controllers using reference designs.  Of course, the NS controllers could be counterfeit...

I've used DC-DC reducing (buck?) controllers I bought for a dollar or two and the power appears stable so far.   No protection designed in for overload though.