I agree with Stan, you don't want to ask the "what is it worth" question. No good will come from it! A $15k '85 5spd car with high-ish miles would need to be in CONCOURS WINNING CONDITION to be worth anything close to $15k! You can get an '87/'88 S4 5spd in close to Concours Winning Condition for $15k...certainly you can get one that will only take elbow grease to get it to that condition!
James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black