Example: $100 Dollar Level, tshirt + coupon for discount on items that we sell, available for use on target completion date (which just happens to be projected cost of baseline project item)?
Edit:
Found the answer...
> Discounts, coupons and gift certificates - Offering a reward at a lower price than what it may cost post Kickstarter is fine, but a future discount or coupon as reward is prohibited. Additionally, vouchers in exchange for a particular item (a meal, a book, etc.) are fine, but monetary gift certificates are prohibited.
A little disappointing, but I can understand why they'd take this stance. (Likely because of money transmitter laws.)
(It's possible you could still phrase it as equivalencies, eg, "one X, OR two Y, subject to availability")