Bill, there is wide variety of track and turnout options available for 2 rail O scale, and Proto48, what to use really depends on the level of detail fidelity one is seeking to achieve. For just starting out in 2 rail you'll likely want to go with O scale, going down the Proto48 rabbit hole is awesome but not for everyone. 
The following link is a good starting point to begin your research
As for me, I've been building my own turnouts for as long as I recall and everything I need for that I get from Right O Way. There are a number of really nice commercially available ready to run turnout options though too. I used to use flex track for all my track work and always liked Micro Engineering's code 125 weathered flex track for O scale or Right O Way's code 125 NS weathered flex track for Proto48, but Atlas's O scale NS code 148 flex track is really nice too and very easy to work with. New ME flex track is generally stiffer to work with, especially their weathered versions, but personally I've never found that to be an issue. I hand lay all my trackwork now though so everything I need for that I get from Right O Way.
Anymore I'm not sure where the best places are to purchase Atlas and ME flex track, and O scale ready to run turnouts, but I'm sure there are others here who can chime in about that.
John
