I think your best resource is the people at work who got you thinking about this ( That's not to downplay the already good advice that others have already given you. ) Ask them if they would be willing to look at some bikes on Craigslist with you, give you some pointers about routes, that sort of thing. We are generally more than willing to throw ideas your way, but we don't know you, we don't know your area, local knowledge and help is probably going to be more accurate.As far as budget is concerned, if you really get into it, and your situation permits, being able to sell your car can be a serious game changer.

I know if a co-worker wanted to get into bike commuting, I would be more than willing to go bike shopping, help fixing up a bike, even doing escort duty for the first couple of rides.