I don't mean to sound like a sceptic, but i seriously doubt that. Basically the only collectible early 80's mustangs that have any demand are the anniversary mustangs ('84) with the GT350 stripes (more valuable with the 5.0L than turbo 4). The '79 pace car, the '84 to '86 SVO, maybe even the early 80's Cobra, but unfortunately your car, although it may be pretty rare is probably not worth all that much just for the fact that it's not a special production car and many people don't specifically look for your car. Because of the options on my car, mine is fairly rare as well (i think only 5,000 5.0L LX hatchs were made in '84 from what i've read, and mine has REALLY odd options), but unfortunately it doesn't stand out enough from the others to really fetch any value (plus my car is beat up, so that disqualifies it instantly).
The only way to figure out just how rare your car is, is to find out the exact production numbers. Now if your car was a GT and was a convertible 5.0L the value would be substancially higher. I believe '83 was the first year for convertibles, but i may be wrong, so that may be the reason for the small production numbers. Maybe in 15 to 20 years your car may fetch quite a bit of money, but i doubt too many people would pay 10,000 for your car when they could get any of the other rare vehicles for much less. I may be wrong and your car could fetch quite a bit of money, and in that case i hope i'm wrong so it works out for you
------------------
'84 Mustang 5.0 LX
My car