I am looking at getting a  older 4 hp evinrude motor from a guy from the local classifieds. He was asking 300 and I talked him to 150 because it hasn't run in 2 years. the gas is stale in the tank. It probably needs a tune up and carb cleaning he says. is there anything that I should look for before buying it. how hard would something like this be to get running.

Here is what I would do:

1. Check the compression with a compression gauge.

2. Check to make sure the motor has spark.

3. Look inside the gas tank and check for water or rust.

4. Check the lower unit oil for proper level and contamination.

5. Make sure it will go into forward, neutral and reverse.

If those all pass the test, you should be able to get it running without spending too much money.  A carb rebuild kit is cheap, a motor rebuild isn't.  It may be very simple to get going or it may not.  If it was stored properly, you may only need to drain the gas and flush the tank.  If the gas was not drained out of the carb and prior to storage, you will likely have to get a carb rebuild kit.  Let me know if you have any more questions.