Find out if it is a pre or post 64. The pre-64 will have cut checkering on the stock and the post 64 will have impressed basket-weave pattern on the stock. Assuming good to very good condition, I would say a fair price on a pre-64 is $650 and a post-64 to be around $550. More accurate description of condition could change this +/- $50-$75. Should have a front sight hood as well (doesn't really affect value but something to consider). Also make sure you find out if the stock has been cut and a recoil pad added. This is common and affects the value especially in the pre-64s. Check the length of pull (middle of rear sling swivel to end of stock) to see if it has been shortened. Mags are not impossible to find but could run you around $100 (not worth it or necessary in my opinion). Although the .308 is the most common 88, it is getting harder to find nice ones in excellent shape. Let us know how you make out with it, I'm sure you will love it. My 88s are my favourite rifles. Upload some pics if you do get it. Good luck!