Well, if it is just for the den, there are the non running "Riva Aquamara" models for a fourth of that price.
It seems to me that Kyosho offered an abs hull chris craft for a while, but I can't seem to find any references for it. A Dumas kit may be your only other best option. If you enjoy modeling at all, these kits are not to difficult to build up.
See Pat Tritles Thread here, http://www.rcgroups.com/forums/showt...ht=chris+craft
Or a first time scratch built Riva, here