The canned malt is probably expired and not usable as are the hops.
If you have a list of items already then check the catalog/on-line prices at midwestsupplies.com or some other supply store and divide by 50%...that's the starting price, now it's time to make your deal.
I wouldn't add in the cost/price for the hops, malt or bottles in my calculations, but if you think it's a fair price then go for it.
As far as I can tell, all you're getting that's usable are two 5 gallon glass carboys ($10 each used), a fermenting bucket ($5), some caps ($3) and airlocks ($1 each). Not worth $100. in my book....$30 TOPS for all of it.
But, hey, that's just me.