I've bought several on ebay. The first, my Bernina 830 record. No problems at all, and it was from a private seller. I bought a Janome serger, a pfaff serger, an Elna air electronic, and a brother embroidery machine. The UPS guy dropped the embroidery machine walking up to the house.
All in all, they were all packed well and arrived safely.
I did have to have the Elna serviced, but it was like brand new and had been used to little that it was "seized" up. They fixed 'er up and she purrs like a kitten. All in all, I have had good results with ebay. However, I do check their feedback scores and if they don't have 99% or above I'll pass them up. Also absolutely make sure that it is insured.