Re: what to do...
unfortunately there is probably no everyday car on the planet that you could have bought in July and it be worth the same amount as you paid, 6 months later- especially with the credit crisis. You will probably need to either keep what you have or set more realistic expectations...but the plan you envision is somewhat of a stretch.
Alter your plan and get the SRT-6. The 6 is leveling off quicker than what you have now, so even with what you lose now, it is PROBABLY a better value in the long run, to trade to the 6...good luck.