Given the limited number of these cars, and given your price range, you're probably looking at 06 and 07's. The 08's and later likely are out of that price range.
So you're looking at 700, MAYBE 800 cars in the US. A number of them have either been wrecked or turned into track cars. So at any given time how many, in any color/option package, let alone what you're looking for, are actually for sale?
Your checklist suggests you're maybe not as flexible as you think.
Better to say: "In market for an Exige, XXX miles, max, here's my budget" and just see what floats in. You can always ignore those not equipped the way you want, or the color you want.
Well, to a degree, that's the point - my checklist is not a hard checklist and everything is negotiable. There are definitely things that I would prefer, but the hard list is simply that's an exige as opposed to say... an elise (no bad will to elise, I just have a thing for the exiges). Ultimately, if someone is thinking about moving on, I would love to understand and consider what they may have.
I can absolutely stretch for the perfect "one owner" type car, if it presents itself, but would be more comfortable with spend in a middlish 40's range for something with something miles and light mods (battery, radiator, exhaust). If to say anything, I'm not really in the market for a premium preserved < 5k miles car.
My ultimate order of preference is Color -> S/C -> -> miles at 40kish -> equipment; looking at a modded '06 or a '07 S, I fully realize an S240/260 would take more dollars and would step up accordingly.