A smart workout mirror is built to replace a gym membership, so it needs to last at least three to five years to break even. Buy a display with solid hardware that will not turn into a giant paperweight if a company updates its software or changes its class roster.
New models drop right around the New Year, which means last year's hardware gets heavily discounted in January. Grab the previous generation during holiday sales; the core tech changes slowly, so you get the same workout for hundreds less.
An intro window is a fixed deadline, not free money. If you still have a balance when the 18 months end, high regular interest charges apply to whatever amount is left.