When buying a used electric typewriter, test the machine prior to making a purchase, confirm that it is possible to obtain ribbons for it, and compare its price across multiple resources. Purchase from a refurbished typewriter dealer to obtain a warranty or repair protection on the purchase.
Inspect a used electric typewriter in person whenever possible to identify any issues or damage that can affect its functionality, and thus its sale price. Test all the keys to make sure none stick, examine the ribbon loader for any breaks, and plug it in to confirm that the electrical components still function. Many private sellers do not offer any buyer protection or refund options. Some auction sites, such as eBay.com, offer protection in the event of a fraudulent product listing or similar incident.
Before committing to a purchase on any electric typewriter, find out if it is still possible to purchase ribbons for it, as this can affect the long term cost of the unit. Research prices across auction sites and specialty retailers to make sure the price being asked for a specific electric typewriter is appropriate. EBay.com offers a historical sale search tool that allows you to see prices already paid for similar typewriters.