You can do an AWFUL lot with inexpensive stretch bands, your own body weight, a fitness ball and regularity of exercise. There are manuals and guides available on the internet. Planks, pushups, bridges, wall squats, body dips (you can do them on a chair), pullups (some pipe between some rafters in the basement/garage), crunches - (check out George Forman's technique - it is best).
Beyond that, some barbells, but they have gone up in price lately.
The major problem is motivation and keeping it up.