....to go with this sub
Alpine Electronics - Type-R 8” (SWR-8D2, 4Ω) Enclosure System

What would a good match - price/quality wise?
Looking for just a mono amp - with a good matching power capacity for this sub...nothing more.

 

Quick Google says 150-350 watts RMS, and peak of 1000W @4ohm

So, Boom: JL Audio JX500/1D - JX
300 W x 1 @ 4ohm, and setup for a sub with a response range of 50-200 Hz.
Plus if you listen to a wide variety of music, the remote for the base boost is a really nice feature.

I've had LOTS of different amp/sub combos in all of my cars, and once I went JL I won't ever run anything else/

I had an XD400/4 bridged on two channels pushing 200 watts to my JL 10w3 in a custom built enclosure and it ROCKED in the Fit.

Actually, the XD400/4 - Car Audio - Amplifiers - XD - JL Audio let me throw 200w to the sub and 100w to each door and was super small and easy to mount. It's a little $$$ but WELL worth it if you decide to go with an all in one solution. I LOVED mine, but it was stolen out of my storage by Termite people

 

Why not just stick to the same brand, Alpine amps are actually very nice. Here's a link to a perfect match for your TypeR sub.

http://www.ebay.com/itm/Alpine-MRX-M55-550-Watt-Car-Monoblock-Amplifier-/181168634174?pt=Car_Amplifiers&hash=item2a2e7df93e

 

I've been doing a ton of reading since my original post.....and I've nearly come to the same conclusion.
There are a bazillion amps out there, and a ton that would fit the bill, but the MRX-M55 and MRV-M500 seem to be a perfect fit...and their price is very reasonable...and can't find any technical reasons on the 'net to steer away from Alpine amps.

Another one I'm considering is the Rockford Fosgate P300X1.
But, I'm still totally open to suggestions.

Another question I want to throw out there though - Will it be an issue, for heat, to stuff a Class D amp under the back floor? I've not had a Class D amp before so I've got it stuck in my head how much heat these amps normally produce...and can't even begin to imagine putting one under the floor in that small concealed space!