You should set up and save a search on "Westinghouse vintage electric lawn mower" on eBay
and have it email you any time someone lists a mower or a part. Unless it looks like classic mid-century design (all the rage on Mad Men and similar film productions) it probably doesn't have a huge value. If you check the "completed listings" at eBay then you can see what actually sells and how much it sells for. This is much more useful than looking to see what the initial asking prices are on listed items.