An ultra-short throw projector is a permanent investment that should anchor your living room for at least five years. Focus on build quality and light output so you aren't stuck replacing a dim unit when the next iteration hits the market.
Wait for Black Friday to snag the current model at a discount. If a new version launches in the fall, last year's model usually sees a price drop that makes it the smarter buy.
Remember that the 0% period is a deadline, not free money. If you have a balance remaining after 18 months, you will start paying interest on the leftover amount at the standard rate.