Anyone have any thoughts on a 1996 champion 181 it has a 150 mariner efi

The seller wants 5k

Any pictures?

Champion made great handling boats but with any used boat condition is everything. If you don't know a great deal about bass boats perhaps you should pay a professional to inspect it. Could be money well spent.

The champion 181 was a great hull for its size.  Most Champion hulls ran well for their size!  I know, I was interested in the 186. I test drove 2 of them.  My wife and I changed our needs to a fish and ski instead so we bought a 20 foot ProCraft.  5K is about right and personally i prefer the efi and carbed motors over the early Opti's for reliability.  

Look the boat over and arrange a chance to run the boat.  If you are still serious, offer to pay to have a mechanic test the compression and look the boat over for you.

I also recommend you read a paper a friend of mine wrote on purchasing a used boat.  Bryan has written a fact filled primer on the subject.  

Get yourself a beverage, kick back in your chair and click on this hyperlink:  The Under $10K Bass Boat Buyers Guide  It is not just a how to, as he wrote it he lived it, sold a boat, searched for a boat, found and purchased a boat.  Good Luck with your boat search.

The value of that boat will be mostly in the condition of the boat. A faded out, beaten piece of crap is not going to be worth what a garage kept babied specimen will be. 

You can't go wrong with a Champion. Solid dependable boats. The mariner wouldn't be my first option, but every manufacturer has issues. It's all in maintenance and luck. Pictures would help, but if it's clean you aren't getting hurt.