1) Don't discard used equipment, but be sure and pick up a good deal on other people's discarded equipment (if that makes any sense). Used equipment can provide you a really good deal because some people (myself not included) go on exercise binges and buy equipment that they just quit using after a month or two. Their investment can certainly be your gain. Look through classifieds and on Ebay to research the best exercise equipment that you can possibly afford. Often times, you will find that the equipment that you are after is priced very reasonably.
2) Consider buying commercial fitness equipment. A lot of the time, the regular home gym equipment that you want to buy isn't what you are used to using at the gym. Find out what types of stuff you like the best and do some due diligence. Look for commercial fitness equipment dealers and you should be able to shop for the same stuff that the local workout spot has for you.
3) Get knowledgeable about the different types of home gym equipment. All equipment is not created equal. Figure out what the different types of equipment are and what the advantages and disadvantages of buying different stuff is. There is an large array of equipment available. Make the right decisions.