Garth, one can say (and the CR List often does) much pro and con about the PX-10. But saying that "parts are difficult to locate for reasonable prices"... I honestly don't think you'd find that to be case at all.
Two weeks of eBay surfing and you could outfit a PX-10 frame with most of the essentials. Indeed, there have been been some swell frames (including a lovely one c. 1970 similar to mine) that have gone cheap as well as complete bikes. Remember this is bike boom stuff and if some folks sneer at the PX-10 for being common and ordinary, it doesn't follow that parts are elusive and expensive.
The hardest to find items are, in my experience, Simplex skewers with the little Delrin wingnuts (there must be 2,854 of these in the hands of four collectors in Japan) and the Ad-Hoc frame pumps which also seem popular in the Land of the Rising Sun.
So if you find yourself tempted, you won't be disappointed. Just don't follow your friend's example and put Campagnolo stuff on it. The lugwork will still not be up to some people's standards and it will shift like.. well that's another argument for another day!
Peter Kohler
Washington DC USA