USPS is where it's at, I've shipped so much stuff overseas with it (Dual Rectifier to France, guitars in hard cases to Sweden and the UK, bunch of small shit to Romania, Brazil, god knows where else), and the rates are fantastic, at least compared to UPS/Fedex - I guess it's true that tracking isn't possible, but hey, that's not my problem!
(and more importantly, it hasn't been an issue thus far, and I always get insurance). And the same with things being held on customs on their end, presumably the buyer knows the risks (and the customs form is easy enough for me to fill out, and I usually just charge a little extra when shipping internationally to cover the minimal hassle)