A great mechanical keyboard is a tool you use for eight hours a day. It should last you at least five to ten years if you buy the right one. Instead of settling for a cheap plastic board that rattles and dies in a year, it is smarter to invest in a solid, hot-swappable deck that you can repair and customize. Watch out for the annual release cycles; last year's model is usually just as good as the newest version, but it often goes on deep discount during major retail events.
A solid deck runs about $250. You do not have to drop all that cash at once. By using the right card, you can spread that cost out over a long runway without paying extra for the privilege.
Keep in mind that this 18-month window is a strict deadline, not free money. If you do not pay off the full $250 balance before the promotional period ends, the remaining amount will start racking up interest at the card's standard variable APR. Set your autopay and stay disciplined.