Check the complete workstation
A tabletop, an underframe and a complete desk can all appear in the same selection. Note what is included, the depth available for a monitor and the legroom. For an office chair, check the adjustments actually present on that model rather than those of a similar variant.
A motorised desk cannot be compared directly with a fixed version. Check the article number, control unit, power supply and listed accessories before using the new price as a benchmark.
Check the adjustments before you buy
Ask to test the height adjustment and controls, as far as the store allows. Inspect the cables and visible parts without dismantling or modifying any electrical components; if there is damage, get qualified advice.
For a chair, check the seat, backrest, castors and adjustments. Also plan how you will transport the desktop or the chair: their real bulk can make a distant offer less worthwhile.