http://mazdagear.com/frontairdamperformance-c01-protege4dr.aspx
That's the only place to buy one new. The only other option for that lip is to wait around until someone sells one used which is a rare occurrence. If you don't want to spend that much money, some people have used lips from Accords, Civics, and a few from Integras. Or you can a "home depot lip" You have to get creative with these bumpers...I personally have a Civic lip
I figured the same thing when I first found that site a few years ago but someone bought one from there just recently. I believe it was Alex (ffocused). With my Civic lip it was $36 shipped, then $30-ish for paint and what not. If it scrapes or gets screwed up no big deal, it was cheap and can easily be replaced, where as the oem lip would make me pucker everytime it came anywhere near scraping since they're so expensive. Civic lips don't look terrible but since eGay quality is hit or miss you can get one like mine that is warped so one side bends in and one bends out...but oh well, it's something lol.i'd be willing to bet that site has no stock available. the mazda accessory front lip has been out of production for a looong time.
an alternative would be to get a civic or accord front lip and modify it to fit. it wont look as good, but will be quicker and easier to find.
http://www.mazdas247.com/forum/showthread.php?123802408-Interchangable-parts-thread/page5
read post #67, that user states you can use a corolla type s front lip. thats what he has on his car.