welcome Katie!
The cheapest form of lifestyle change I know is simple calorie counting. We have a whole forum for that and there are several free online calorie trackers.
http://www.3fatchicks.com/forum/forumdisplay.php?f=172
And as for exercise, walking and pushups, situps, etc. are all free. And you can get exercise videos from your library if you are interested.
Keep posting in lots of places and we will help you get started!