I work at a BMW dealership and we do clear-bras here. I can say they are great. Prices vary but most are around $500 to have done, some more some less depending on how MUCH of the hood and bumper you want covered. I have seen some nasty rock chips in bumpers and scratches from curb rash, and they rip the clear bra off and everything goes away. Brand new car underneath. Its a nice feature to have on a car, especially if you do lots of highway driving. MOST companies that do clearbra have a plotter that already has the predesignated cuts for your model bumper. The clearbras for the BMWs are very hard to see since they are cut near perfect around the body lines. BUT that all depends on the quality of the machine and installer. Many shops might not have this and might have to put them on by hand. WHICH, might look crapy (or at least not near perfect).
clear bra's work great, and after years of use you are able to take them off and have a brand new car underneath, and then replace the clearbra with a new one.
The downside is that
1) you obviously can't wax the car with one on it, so i'd probably recommend having that done before you put the clear-bra on.
2) since the clear-bra is a clear vinyl material (just like the solid vinyl stripes on the gt500) I'm not sure how easy or hard it would be to remove after a year or two of use. It MAY take your stripes off with it. Which would be a pain to have to re-stripe the front of the car too. Now I may be mistaken, but its something to think about, since you basically are "putting a sticker over a sticker".
3) there ARE different qualities and different thicknesses of clearbras out there. I'd recommend asking around. I believe they are sized by "mils" like 3mil 5mil etc. Some are thin some are thick. So try to go to a shop that does it and see the different sizes or thicknesses (if they have them). Most likely, the price differences you will see in pricing clear-bras will probably be based on the thickness that the shop uses.
4) if you let your car get dirty, the edges around the clearbra will attract dirt, and you will start to see the outline of the clearbra...which isn't attractive. Having a nice dirt line around your car.
Having said that, I still don't think I'd get it on my GT500.
1) too expensive for me, that is mod-money I could spend elsewhere =)
2) I am very anal, and while it is a "clear bra", even the BEST models are still visible to me (and I think the GT500 stripes would make it stand out even more), and I dont like that.
3) For the price of the clear bra you seriously could just go get your front bumper repainted once every 2-3 years just like you would have to spend $500 when you get a new clearbra every 2-3 years.
4) Like I mentioned before, I'm not sure how even putting the vinyl clear bra over the vinyl stripes would pan out when you wanted to take them off. And even though my family has their own vinyl sign shop and have made my own stripes on mustangs before, I dont think i'd want to go through the hassle of restriping the front of the GT500.
5) Since clear-bras are vinyl, basically one GIANT sticker, they too must be installed carefully. Just like you can have air bubbles or wrinkles in your GT500 stripes, you can also have these present in your clear bra. So you must make sure the shop you take it to does a great job.
Just my 2 cents