The amps were cheap and the capacitors failed, killing the amps. It is a fairly common issue and isn't limited to JBL, but that particular sub had a very high failure rate. A buddy of mine came home one day to his making a very loud "thrum" with smoke as well. When he contacted JBL they acknowledged the issue and offered him money toward a replacement sub. The HSU I listed is above the price you were asking, but it will easily best the JBL.
The NSP1s were a surprisingly decent speaker at the time. I setup a system based on them for a friend and though they lack deep bass, they sounded good.