As people's disposable income becomes smaller and smaller, and the cost of living - food, interest rates, mortgages, rent, gas - increases, the power of barter and trade will be greater. In many rural areas, people have fewer dollars, but more 'stuff' just laying around. When you advertise things for sale, try adding a line at the end of the ad offering barter or trade for items that you need, be it livestock, fencing or other homesteading items.
One of the most important things to consider in a barter situation is to be realistic: in an ideal trade, both parties should leave the exchange feeling like they got the better end of the deal. Haggling and negotiation is acceptable, but it's important to consider the true value of these (more than likely) second-hand items.
Bartering also facilitates two other things which are essential to the homestead: recycling and shopping local.
The sheer amount of waste that we as human beings produce is incredible. We live in a throw away society and are encouraged in so many ways, not least by the horrific quality of the majority of commercially manufactured goods, to simply discard and replace items, or throw away what we no longer need. Hopefully, as bartering opportunities increase, this trend can, in fact, decrease. One man's trash can, in fact, be another man's treasure.
Shopping local is very important for the health of your local community, small farmers and mom-and-pop business owners. You'll be hard pressed to find a Walmart or a Target who accepts barter, so make the most of your opportunities to barter and trade as part of private transactions and save your cold hard cash for paying for things where only cash will do; electricity bills, gas bills, etc.
It seems that bartering and trading will become more of an option for people from all walks of life as there seems to be little light at the end of the tunnel where cost of living is concerned.