You really wouldn't need anything else for in sump use besides the base plate, for in tank I would use a mag holder like 6080.500 and forget the holder set. Value is relative, a new model is coming at months end and will further reduce the value. My guess would be roughly $200 with the base plate, there are alot of people leaving the hobby with the economy as it is so that factors in, I would guess on eBay you could get $150-$250 if you had all parts and it worked. It should easily handle a 120 or less mixed reef, 90 all SPS or a 180+ fish only or FOWLR. For it's size it is a pretty darn good skimmer. This is one of my favorite models, it works well and is easy to use and will generally last a long time.