I sold one of those Waldenbooks TSR dice bags last year and got about $10 for it, though I paid over $30 to get it originally on eBay.  This is the kind of tricky item that you could do quite well on if you get two big bidders involved, or you could be left holding the bag, literally with only one or no bidders.  

I'm sure others here can give you a better idea of Dragon mag values, but generally they haven't been very good except for the under #40 issues.  You might want to put them up as a lot and see if you get some bites, but I think even the resellers would probably give it a pass unless the starting bid is cheap.  Shipping is expensive for all those mags obviously.  But perhaps others here would have better advice on that one.

MERP box set (8100) - depends on condition but I would say from $10 to $15 plus perhaps another $7-12 for the screen.



Here is one (incomplete) box set up for BIN.



http://cgi.ebay.com/MERP-rpg-Middle-Ear ... dZViewItem

You might want to try a local used bookstore and see if they would be interested in the Dragons.  My local store buys dragons for $1 each and sells them for $3.  I pawn off Dragons and D20 stuff there for more than they would sell for on ebay.