As much as we'd all like to believe this chick was 'disgusted' with the idea of a P5 having an A/T... I'm willing to bet she was either turned off by something else (or that it might have all just been in your imagination) You're clearly not fond of the transmission... so your perception of people's reaction to your car might be skewed because of it.
Regardless of that, the idea that this car was too good of a deal to pass up is somewhat hard to believe. Give us the details of the car and we'll be the judge. All things being equal, a stick shift is going to sell for far less. A) it's less expensive to make and B) (most importantly) less and less people know how to drive one. Granted, this logic doesn't always hold true on every car. I'd like to believe it's the opposite on a performance car but then again... with the amount of toolboxes I see driving automatic Vettes... ya never know. Either way, you should've looked harder for a manual. Hopefully you were kidding about a tranny swap since that contradicts the idea that you're on a budget. To a lesser extent, so does virtually any mod (including those coilovers.) Why put money into a car you admit to not liking? Instead, you should try to sell it. If it was as good of a deal as you say, you might not lose any money. Hell, you might even make some! Without doing any searching... I can guarantee you there's a car out there that fits your needs (and budget) better than your current ride. The state of the economy these days equates to arguably the best time in history to be in the market for a car. Assuming they can afford it, nobody (in the market) should settle for anything less than what they want.