To be honest i dont think an Audi really seems like your type of car.
You have 3 loudly modified cars, and this style of modding is something Audi drivers pretty much 95% of the time keep away from as they value the fact that Audi employ people and pay them 100,000's a year to design good looking cars, so its not a good idea to ruin them with stick on bumpers, spoilers and exhausts.
You dont have to be a genius to discover Audi will launch a new engined version of the R8 within the next year or so. Rumours are it'll be a V10. This information is pretty solid, your dealer isn't taking much of a risk by telling you this. You would be pretty dumb to give him $1000 of your money for him to gain interest on for a year before you actually garentee your order. Even still you will not get the first R10 in the US as many who ordered had their orders bumped back due to demand from VIP's and so on, this means he has your money even longer!
My advice would be to keep your money, do a bit more shopping around, if when the R10 finally shows up, and your still interested and your able to actually spec your car, then put a deposit down.
PS - Supra