I like Alex's idea about bonus rewards. T-shirts are a cool idea as well, especially AoS patterns.
I like the idea of clips, but rather than deck-themed clips, why not just plain ones? Let's face it, someone buys six of your decks, sooner or later they get used up, and maybe he'll want to use that clip on a different deck. Ecos, Porpers...unique COLORS are great, too.
Posters, art prints, etc. - I was never a fan of them. There's only so many places in any home to hang these things.
How's this for an overfunding bonus - gaff cards. I loved the extra gaffs for the Watcher deck and Blaine's Split Spades Lions in red and blue. Yes, it would involve a extra print run, but USPC might be able to make you a deal. On a sheet of 56, you could make 5, 6, 7, 9, 12, 14, 18 or more gaffs for each deck sold - they can all be unique or you can make duplicates of some, since gaffs get used and wear out. Make them exclusive to the KS funders. Card collectors also like little extras like that when they aren't available for retail sale.