A great photobooth gives people something to do while the party gets moving, and you get prints of everyone who showed up. The trick is timing. Photobooth vendors book up fast for prime weekend nights, so locking down your rental three months out keeps you from paying rush surcharges or settling for poor lighting.
A typical rental runs about $600 for several hours with prints, props, and an attendant. If you plan ahead, you can give yourself plenty of runway to pay it down instead of swallowing the full bill in one weekend.
Keep in mind that 0% interest is not free money; it is simply a grace period. Once those 18 months expire, regular interest kicks in on whatever balance you have left, so make sure that $33.33 monthly payment is non-negotiable.