Welcome! I'm in the same boat as you. I'm a new member and also looking to buy my first airplane. There is a lot of good advice here and ownership experience. I can provide a little of my research from the last few months. I ran the information you gave through vRef which is like a airplane bluebook service that I subscribe to. Its a good starting point, but there are other factors that might affect the price.
1969 Cessna 150J with 5400TT 1525SMOH has a base retail value of $10,323.09
The base value is for an average 150J is $16,700 assuming 6956TT and 900SMOH
This is just a rough ball park based only on engine and airframe time. Lots of other factors that will affect the price up or down.
Hope this helps. Good luck!
-James
