I bought my '80 152 in March 2001. At that time, it had 9000 TTAF and 2000 SMOH. The seller asked $20K; I offered $19K and he accepted it on the spot. I guess I could've talked it down a little more. But I used to rent it in the previous 6 years and I know it's a good plane, so I didn't haggle too hard. My plane now has over 9400 TTAF and the engine is 30 hours past TBO. Still running trouble-free.
Try talking the price down. I think you probably can get it for $17K-$18K.