Hi Kathy,
Welcome to the wonderful world of pin collecting and trading. There are a number of places you can buy pins and lanyards. I'll start by saying that you buy just about anything from Disney Mail Order at WDW or DL. Those numbers are: For WDW Mail Order 1 (407) 363-6200 and for DL Delivers 1 (800) 760-3566. You can buy Pins, Lanyards etc. from either place. You can also buy Limited Edition pins too, but they have to be released for 30 days at the parks before you can purchase through mail order. As far as Rack pins go, those you can buy whenever they are released. No waiting for those. Rack pins are pins that are always on the racks unless they are retired.
Your other options are Ebay and Yahoo. The people on Ebay and Yahoo are people are selling their pins for whatever reason. I've found that the prices on Yahoo seemed to be cheaper than Ebay, but there are much more pins for sale and a bigger selection on Ebay. Then there is Cheappins.com. This website sells all kinds of pins, not just Disney pins. The prices there are really good. So Kathy, I hope I was able to help you. If you have any other questions, please feel free to ask. I'm sure someone on Disboards will be more than happy to help you.
Joey