What type of 18 is it
an obsidian...? 600rms, but it is the presale. a btl is out of your price range, even a 10 (shipping will kill you). The only DC that you could get for that is probably a used level 3 or lower series. I personally if i had 200 would get an obsidian sub, just have to wait til they are in stock again.
Thanx dude Im just doing this for a friend he wants to buy a sub I already got one