Lizzie,
if a '68 Mustang is your dream car, here's a piece of advice: never, ever drive one! A standard one, in good nick drives like a knackered, drum braked 1100 Escort, but with decent performance. If you're brave/stupid enough to use the throttle. That's not to say that some straightforward upgrades won't improve it, but that's more to the level of a 3.0l Capri.
My boss has an '05 Mustang GT, stock 4.6 with a manual box. It looks great from a distance, but when you get close to it, it looks like somebody increased the vehicle's size by 20% before sending the files off to be manufactured. Unfortunately, it drives the same way. It sounds great, but for a car with 260hp, you're left wondering what they're actually doing. It rolls a lot, being softly sprung, but both the handling and ride are poor, largely due to the 3 link live axle propping up the back. The brakes aren't up to the job, and the interior is really shoddy - look at a 15 year old Korean car for a decent comparison. The reason for much of this obvious: when she bought it new, the American sticker price was about $25,000, which at the time might have bought a V6 Hyundai coupe here. That would make for a difficult decision!