I had a single D3 10 that I kept around the house for when I was between builds. Pretty nice subs IMO. I gave it double, sometimes way more than double its rated RMS and it never seemed to get smelly from overheating. (I don't push my subs to their limits all day either, though).
They sound darn nice and it got pretty low for what it was. I'd recommend them for the right price.....IIRC, they go for like 150 or so new...so I think 150-175 in a box is a nice deal as long as they work perfectly. You may or may not need to build another box for them to get the best performance for them but for 175 with the box, atleast you'll have something to play until u get a box built.
I'd say go for it. I like Diamond products...every thing I've had from them has sounded phenomenal.
I went ahead and picked them up, they sound pretty good for what they are. I got them hooked up to a RF t1000-1bd at 1ohm and they sound louder than the RF t0 15 i had.