Hi M.,
Since you live in Fremont, have you considered Livermore wineries? Some do not charge for tasting, some charge $5 which is refunded with purchase. You do not need to make any reservations either. Wente and Concannon are the big wineries and there are many smaller ones in teh area that are quite good. A quaint spot is Blacksmith Square on S. Livermore Ave - an open patio area with 5 or 6 winery tasting rooms.
A basic limo service company might be less expensive than one that specializes in wine tours - not sure about that though. Do you have any relatives (like your niece) that might be willing to be the driver for a day?
Some of our favorites - If you like zinfandel wine - Livermore Valley Cellars has some of the best locally, great ports at Cedar Mountain .. we like almost all of the local wineries for different reasons and have club memberships at several.
Hope this helps --
E.
I have 2 almost grown kids, a 20 year old son in college and almost 17 year old daughter who is a high school junior. I spend almost 10 years as a single mom and am now happily remarried for the past 7 years