For the broke folks like myself...
A doorway Pull Up Bar
I would consider this piece an essential component for the at-home exerciser. Pulls ups are an all around great exercise for strength, function, and body shaping, and this bar couldn't be any easier to use. It assembles in less then 5 minutes, is made of steel tubing, and does not have to be installed into a wall. Just set it up over a door frame and start pulling. They typically cost about $20 but I found one the other day at a discount store for $13.
The classic cardio tool. You can work on balance, agility, and coordination all while getting in a great cardio workout right in your living room. You can find these almost anywhere and they start at around $5-10. Check out this video for some ideas of how you can use your jump rope.
I bought a set of these at a hardware store a few years ago for less than $10 and I still use them today. All you need is a carpeted surface and you are ready for action. They also make some for hardwood floors as well. You can do a multitude of exercises with them and they can be stored anywhere when you are finished. You can also use them to bust out some hot dance moves...
This one takes up a little more space but makes up for it with cost. All you need is a sturdy bag and some sand. I bought my bag at a sports store for about $7 and I got 50lbs of sand at the hardware store for less then $5. If you google "sandbag exercises" you can see there are endless possibilities with these unique and functional tools.
Going up in cost a little...
These are great for developing upper body strength and building a solid core. They do require some sort of high rafter to fasten them, so if you have a place for them I highly recommend you get a pair. You can effectively train all of the muscles of the chest, back, arms, shoulders, and abdominals with this simple yet brutal tool. They will typically set you back between $40-85 depending on where you get them.
I own a kettlebell and enjoy using it from time to time. There are people out there who use kettlebells exclusively and get great results. They range in weights from as low as 8lbs to all the way over 100lbs. Most people, though, use weights between 35-53lbs. The one drawback with kettlebells, though ,is that the exercises are highly technical and can be hard to learn without proper instruction. If you are interested in kettlebells then I recommend you explore www.strongfirst.com They are a great kettlebell resource. These will typically set you back $75 or more depending on the size.
This is a tool that I own and use/endorse quite often. It can easily be set up and taken down in your home, or taken outdoors, for a great full body workout. It utilizes just your bodyweight as resistance and can be used to train all the muscles/movements of the body. It is also a great tool for building core strength and endurance. These can be a little pricey at around $200 depending on the model you choose. You can get more info on these at www.trxtraining.com
This is likely going to cost you the most but if you are serious about your fitness than it is worth it. Muscle has been forged for centuries with this piece of equipment and nothing will maximize your strength more than a heavy barbell. You will need some space and a hard surface so a garage is an ideal place. It still doesn't take up much space when storing and you will be able to use it for many, many years to come. You can find standard sets of 300lbs. at your local sports store for $250-300. Barbells and plates used for Olympic lifting, though, will likely cost you $500 and up.
If all you did was buy the first four items on my list then you could have a pretty descent home gym for less than $50. But if you wanted to put together one KICK-ASS home gym then you could get all the items on my list for less than $750. You would have all your bases covered regarding strength, stability, power, and endurance. When you think about all the things that people spend money on, a couple hundred dollars is not that much. Especially when it can make a huge impact on the way that you exercise and improve your health. Hope this list helps. Until next time.