Your Marlin model 989 which was a semi auto promotional model will range in price from 75-150 dollar,depending on overall condition.
try eBay that might do .
Try a thorough cleaning, change magazines, change ammunition. The marlin 989 was made in the 60's the bolt does not open when the last shot is fired
Contact Marlin customer service through their website, and request an owner's manual for your rifle. They are free.
what is market price for marlin
On the main Marlin Firearms website, there is a section labeled "Owners Manuals", from which you can download the manuals of Marlin products in .pdf form. Assembly and disassembly instructions should be included in these manuals. See related link.
I have used the 10-round magazine for the Marlin 795 sold by Brownells (www.brownells.com) as 550-000-337. This is a nickel plated mag. Aside from extra capacity and nickel plating it appears to be the same design as the 7-round magazine that came with the rifle (Marlin 989). Brownells also sells a 7-round blued mag as 550-707-346 that should work.
I'm not sure what they are worth now, but I bought one a few years back for around a hundred bucks..
About 550$ less or more
Your Marlin model 81DL was a promotional model that was made by Marlin from 1940-1965.These range in price from 65-100 dollars.
989 = CMLXXXIX