i think that's a really good price for a 15"L7... prices of both the 4 and 2 ohms were identical the last time I looked. If it's brand new, I'd get it.
i've heard that the new L7s use much smaller boxes than the previous L7s, so instead of a 8^3 box (like last year) it would do the same in a 4^3 box (i just used random #s to get my point accross).