UPDATE: Please read my newer post about this issue.
As I started to develop for the iPhones and iPads I purchased iPhone 3G for 50$.
Then I find out that 3G is not anymore officialy supported by Apple and that it doesn’t make sense to develop applications for such “old” hardware.
Yesterday I found that there are custom firmware that could be loaded into the iPhone: http://www.whited00r.com/iPhone3G