What Steve said. Sewing machine oil to clean it and worth is whatever your market will bear. Check out the sticky on cleaning your machine and watch Muv's videos. Also sometimes the cigarette smoke is actually a failing shellac clear coat. Just pay attention when you start cleaning. If the clearcoat is failing you can screw up your decals by over cleaning.
You can check Craig's List in your area for other similar machines to get an idea of asking prices in your area. Don't be fooled by really high numbers. With rare exceptions those people are dreaming.
The Singer 201 was Singer's finest domestic machine when it was made. It actually qualifies as a light commercial machine IMO. They were used a lot by tailors and dressmakers. It would actually be an excellent machine to keep.
It's probably worth more to you as a sewing machine than what you can sell it for.
Rodney