I think your advice is solid, Prism99. You can get a nicely featured brand new Brother machine for $179, so if the Singer was $200 when purchased two years ago, why pay almost $200 to have it serviced.
With regard to oiling a sewing machine - I have a HQ16 that only requires oiling in the bobbin race. All the other potential oiling spots are well greased. My guess is that oil may drip on computer boards inside our fancy, modern machines and cause the boards to die an early death.