A dark basement is wasted space until you put a 120-inch screen and a solid soundbar down there. Movie nights move downstairs, kids get their own space, and the actual setup only takes a weekend if you have the gear ready. The cheapest time to buy AV equipment is late winter, right after the Super Bowl, when retailers mark down unsold projectors and audio gear. If you need an electrician to drop a new ceiling outlet or run conduit, get two or three quotes before you buy any hardware.
All in, a dependable 4K projector, fixed-frame screen, mount, and sound setup run about $2,100. Instead of taking that cash hit all at once, you can spread the cost over 18 months using the Citi Simplicity® Credit Card without paying a cent in interest.
Keep in mind that 0% interest is a strict deadline, not free money. If you still have a balance when the 18 months end, standard variable interest rates apply to whatever amount is left. Set your automatic payments from the start so you clear the balance completely before the promotion closes.