Try www.autobarn.com as they have pretty good selection and prices on PIAA stuff. Plus, if you spend over a certain amount you get free shipping. Good excuse to get that K&N Filtercharger and maybe a tow strap and other goodies... hint hint.

On the horn-lights, I got my 4-LED 194's (green) from eBay almost a year ago and they're still working great. Just do a search on ebay for "194 4 LED" and follow the feedback. Hard to beat for about $10 a pair on average.