I recently purchased and LFM-C and LFM-Plus.
Both were B Stock. The LFM plus B stock is currently $474 with free shipping, which is awfully close to your budget. Other than the subs being about an inch higher than they were listed in their descriptions (which affected where I could place them), I have been very pleased. I use them in one very large room for music only, with 2 LCR speakers driven by an RR2150. I'm waiting for a while before I post a review, but I can say that I'm very pleased with the subs.

I appreciate all the help and input. I had a two channel 550 watt amp already. (Peavey 8.5) so I built a 5ft enclosure tuned to 20 hrz with a 450 watt rms 12" speaker I already had. (Bass for auto industry from 15 years ago when I was even more stupid). The other 550 side I'm gonna use for a mono switcher that i had to send signal from the B from my 950 to the 550 side, to three sets of other speakers ran to my Lani, garage and living room. It works out to a 4 ohm load on each side at 550 watts. But to get the 4 ohm on the B side I have to run two sets of the other 12" speakers in the the other rooms. (16 ohm 12" speakers)