If you don't want to waste money this is what you should do.
Go through the classifieds and buy a HIGH overclocking 2600k. Run the piss out of her at 4.8 to 5.2ghz, whatever you can with the cooling you have on air. Then upgrade your SSD to whatever you prefer. I like the crucial m4s for stability. Feel free to upgrade to a gtx 680, but I wouldn't do SLI yet personally.
Other than that, basically get a system going from the classifieds that is CHEAPER than what you sold yours for, or very similar. That way you come out ahead, get to rebuild a rig, have a higher overclock than you had before, get a new gpu, have a new ssd, etc.
It will feel like a new build, but you won't be wasting a ton of money. It's funny, I have a friend who built a super rig and spent a ton of money. I did a budget build on mine and built it from classifieds / cheap deals etc and it blows his away. aka 2500k vs 2600k, overclock differences, gtx 570 vs gtx 580 *new/used price differences* etc etc etc.
In the end, it's all about the money. Gaining 1 fps which no one can tell the difference between 104 and 105 fps or 46 and 45 for that matter and wasting a ton of cash is pointless. Especially because the second haswell releases you will want to get it and you will be rewasting your cash.
Do the smart thing here and grab another 2600k rig that overclocks higher with better gpu, ssd and possibly psu etc.