I kinda just threw that sub out there... it's been a year or so since I've been active with car audio forums. Looks like they're going to want a little more power than you have (750 RMS for a 10 or 12).
Honestly, a tried and proven sub for sealed or small ported enclosures is the Resonant Engineering RE sub (they have a mounting depth of under 6" for a 12), or if you want to be a guinea pig, RE has a new shallow mount called the SL. They call for 350 watts RMS and have a mounting depth of 3.5".
I haven't ever seen or heard anyone be dissatisfied with RE. I know they were bought out a while back by US Amps (also a good quality company) but still retain their designs. They can be expensive now that they aren't privately owned anymore.
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Looks like they are right around your price range on that site, but that is the only site I looked into. You may find it cheaper. Good luck and let me know if I can help you with anything.