A little help please......

I saw this on a site and been in talks with the owner for about a month now. I know that the systems and disk drives I will be reselling so i need to get them cheap enough that i can flip and profit on them. ( or use them for good trade bait ). BUT yeah want to make sure I make him a solid fair offer that he should be happy with and the fact that I can still make money off of the not needed items. I also have to factor in shipping costs too. ( I figure the books and mags can go media mail, I just dont know what those are worth at all .)