4th order friendly subs, what models well?

[jroo]

Folks, I am pretty set on doing a 4th order build in my trunk of my Volvo. Will port through the Ski hole so looking at 4th order friendly 10" or 12" subs. I wanted to keep budget no more that 300 bucks for a single sub, but the cheaper the better. I have been told that high QTS, low FS, and high VAS are the specs that will generally model pretty well for 4th order. I looked at the Alpine Type S and seems to be a cheap sub that fits the bill, but would like to hear direction on others that work. Again just doing a single sub at around 500 rms. Thanks.

[AlpineNut]

I personally have used the Alpine TypeS and was quite displeased with its performance and i blew 2 of them using a MRV-M500, if you wanna go 1 single 12in get the TypeR they are mean and sound good!  And can handle 750W-3k the TypeS can only handle 500w-1500w.  And depending on where you get it, you might be below ya $300 limit.