Measure before you shop
Check usable capacity and outside dimensions. An appliance that does not fit your counter or cabinet is not a useful purchase, regardless of its advertised discount.
Make maintenance part of the comparison
Filters, replacement parts and cleaning supplies can change the long-term cost. Look up the parts you would need and check whether they are easy to buy.
Buy for the routine you have
Consider how often you will use an item and where you will store it. A versatile tool you use every week can be a better fit than a specialized gadget.