can save about $100.00 flying into sj instead of sfo is it worth it can i catch bart from sj?

If you destination is downtown SF then you really cannot rely on public transport to get you from SJC airport very quickly.

You catch a shuttle bus to the CalTrain station, then take the train to SF. You do not take BART as it does not go to SJ.

I think you need to take into account the trouble, time and cost (CalTrain, taxi from SF Caltrain sta to hotel, etc).

Cat Train takes about 1:40 minutes and then you take a $10-$20 to your hotel, Trains usually run on the hour so you may have to wait. If it was just me and I was staying DT SF and had no business in SJ, I would pay the extra $100, but you do get a good look at the bay area.

see this website. they will do a san jose pick up by pre-arrangement and it's door to door.

the ride in a car takes 45 minutes.

http://www.supershuttle.com/htm/cities/sfo.htm

It is not easy to get from San Jose airport to SF but consider Oakland. There is a shuttle bus from the airport there to BART, then a short ride on BART to SF.

I'd agree to check with flights into OAK. Not only is it easier to get to SF than SJ imo, the flights are often cheaper.