I've had the car for a little over a year now and I just recently spotted the leak on my driveway. I got in a accident last month but she hit me from the rear passenger side so I don't know if that has anything to do with the leak.
Depends upon where the leak is. If it's a hose, probably won't be very expensive at all. If it's the radiator it will be fairly pricey. If it's a blown head gasket, be prepared for sticker shock. If it's a cracked block or head, that will probably cost more than the car is worth at this point.
You are driving a VERY illustrious car here. These cars REQUIRE the use of genuine Audi coolant (made by Pentosin) EXCLUSIVELY!!! NO PRESTONE EVER!!! These cars also require the use of ENGINE OIL that meets their own specifications 502/505 ONLY!!!! NO VALVOLINE EVER!!! Have your engine flushed out and use Mobil One 0W40, total oil, Pentosin oil, or Lubro-Moly oil. THe proper oil will have the name AUDI on the label, as in "meets VW/Audi specification 502/505." ALL OTHER OILS AND COOLANTS WILL DESTROY EVERYTHING OVER TIME!!! If you have developed a leak, it MIGHT be from your water pump if you are nearing the 100,000 mile mark. You will require a timing belt servicing that includes NEW belt, water pump,pulleys, coolant, etc. THere are entire timing belt kits available from CONTINENTAL as a package. Go to BLAUFERGNUGEN web-site. They have entire kits including the proper engine coolant for around $240. If your coolant is GREEN, somebody somewhere has fowled your car up. Your engine requires blue, rose or violet coolant. Drive your car over a quicky lube pit to see where your leak is coming from. HOW MANY MILES WITH WHAT ENGINE?????? Any other coolant will rot the plastic in your expensive radiator tanks and cause extensive expensive trouble over time. GOOD LUCK!! Unfortunately, the 2.8 liter engine requires special knowhow and tools to change the belt and the other stuff. In Detroit area, I can rent these tools when I need them. Where are YOU???? You will need to have your CRANKCASE VENTILAcleaned out too. If you remove your oil filler cap and the inside of the engine is coated with brown tarry goo, you will have to have it removed!!! THe dealerships have a special machine that does this. STAY AWAY FROM JIFFY LUBES!!!! once again, NO VALVOLINE EVER!!!!