A good standalone VR headset should be an entertainment hub that lasts you at least three or four years, not a novelty that gathers dust after two weeks. If you want high-resolution displays, sharp lenses, and enough onboard power to run games without a PC, you are looking at about $1,100 once you factor in upgraded head straps and accessories. Buying the right kit upfront keeps you from upgrading twice.
Timing matters just as much as hardware specs. Manufacturers almost always drop their major hardware announcements in autumn. Buying in mid-summer is usually a mistake, because you either miss the newest features or overpay for hardware that is about to see an immediate price drop.
Keep in mind that an 18-month 0% intro period is a hard deadline, not free money. If you have any balance remaining once those 18 months are up, standard variable interest rates kick in on whatever is left, which quickly erases your savings.