Repairs are expensive, but if you're willing to do them yourself and realize that german parts cost more $$$ you'll be alright. For modding, the 1.8T is the way to go as the 2.8 has a very limited aftermarket. Audi's aren't cars for everyone, if u're willing to stay ontop of maintenance and get a little dirty they are fun and rewarding cars that you'll have a lot of fun with. A general rule of thumb is to expect at least $1k worth of repairs per year.
Search www.audiworld.com or ask if you need more info.