I needed an iPad 1 to test my next release, and instead of using eBay as I usually do, I noticed that Amazon has a substantial selection of used items. I ended up getting an iPad 1 in great condition (perfect screen, one scratch on the back) for $125, without the extra hassle of eBay. If you need an older device, either for compatibility with the older 30-pin dock connector or just to save money, give it a try. Here are links for iPad models 1, 2 and 3:
Used iPad 1 - limited to iOS 5, which excludes some app featuresUsed iPad 2 - runs latest iOS, but no Retina displayUsed iPad 3 - Retina display and last iPad to use 30-pin dock connectorI don't know if these are available outside the US ... maybe someone else can comment on how this works in other countries.
P.S. If you use the links above, I'll receive a small commission.