swt it's not oil, it's anti-fog solution applied by factory.

cheap replacement:

1. buff with baby shampoo one drop on each lense, rub nicely with cloth before taking goggles for a swim.

2. forgot to buff before going to pool, no worries, collect some spit in your mouth and spit once on each lens and rub nicely with fingers. Then rinse once in water.

both methods are good enough for one swim session (because you'd rinse your goggles with tap water after use).

what is your budget and what do you intend to use it for? if just to use the stopwatch to track your lap time. I just use this one:

http://www.mudah.my/CASIO+STANDARD+AE+1000...ch-42504119.htm

I bring to dive in the sea also no problem.