Price is only part of the deal: check size, condition, safety labels and collection costs.
The useful answer
Before travelling, confirm exact measurements, stairs, whether the item comes apart and any damage. Check upholstered furniture for its permanent fire-safety label; ask to see electrical items working and avoid damaged plugs or uncertain provenance.
Bring a tape measure, boot dimensions, blankets or straps, and enough help. Add van hire or delivery to the total—a free sofa can still be expensive.
Inspect in good light and keep messages inside the marketplace. Pause if a seller pushes for a transfer or will not let you inspect the item.