There is an abundance of exercise equipment available. It is difficult to know what will be a worthwhile investment. Exercise equipment can get pretty expensive but there are items out there that won't break your budget and will give you a lot of the same benefit. One piece of equipment I personally love using during my workouts are resistance bands.
Inexpensive
You can generally find resistance bands for about $5.00 to $15.00 with a variety of different types and also resistance. Some resistance bands are strips of elastic material and others are tubing with handles for better grip. Resistance bands also come with a variety of resistance levels. Thicker elastics or tubing (different colors) are going to give you greater resistance.
Benefits
The beauty about a resistance band is that you can add a resistance band to almost any exercise to add a little more...RESISTANCE! By using a resistance band you make the muscle work a little more and as a result your muscles are stronger and more toned. Resistance bands are great for strength training workouts, increasing coordination and balance, you can them with you when you travel, and they are great for all fitness levels.
Examples
Back
Sit in a chair or on the floor with your legs straight out in front of you. Loop the band around the soles of your feet so that the band is tight. With your palms facing each other, breathe out and bring your shoulder blades together. Bend your elbows and bring your hands to your chest. Repeat.
Biceps
Stand on the band with knees slightly bent. Keep your elbows to your side and palms up. Curl your arm up toward your chest and lower slowly. Repeat.
Shoulder
Sitting or standing on the band, hold the band in each hand at shoulder height. Extend the arm straight up, but do not lock. Slowly lower arms and return hands to shoulder height. Repeat.
Squat
Stand securely on the band with both legs about shoulder width apart. Keeping your head up and the back flat, bend your knees like you were going to sit in a chair. Do not bend the knee past 90 degrees. Make sure that your knees do not extend out past your toes. Repeat.
Triceps Press
Keeping good posture, sit on the band. Place one hand slightly behind your head with your elbow at your ear and palm facing upward. Straighten your arms over your head. The elbow should be slightly bent throughout the exercise and you should lift and lower your arm slowly. Repeat.
Band Pull Down
While sitting, hold the band with your hands about 12 inches apart. Extend your arms over your head. Keeping good posture, pull the band so that your arms are out to your side. Make sure that your elbows are straight and in line with your shoulders. Return under control to the starting position. Repeat.
Chest Press
Sitting or standing, center the band on your upper back and shoulders. Adjust resistance by wrapping band around the hand (palms should face downward). Keeping the elbows slightly bent, pull the band out in front of you. Repeat.
Example images are from the Utah Department of Health's BeWise Program.