welcome to the boards. this is the wrong place to post this kind of request. but regardless, your best bet to find parts is to search bricklink
. the user interface takes some getting used to but you should be able to find what you need by doing a catalog search: http://www.bricklink.com/catalog.asp
you can either do an inventory lookup of a specific set that has the tracks you're looking for and then browsing the sellers that offer that part, or search for the part directly and skip a step.
if you have any questions or need help with using bricklink, feel free to post here.
going to move this to general lego discussions as i suspect our new user does not yet have access privileges to b/s/t.