I have been doing some research into availability of iPhone 3G complete screen assembly and its not looking good.
My sources in China inform me that its not available anymore, only the separate parts.
So it seems that there maybe a block by Apple for this complete unit to be produced for some reason. It was available and now has been discontinued.....this would also explain why pdaparts.com are also unable to sell the item.
This leaves the users in a dilemma: we have to try to effect repairs using the parts which means we cant get a proper seal of the glass to the frame which houses the LCD panel and digitizer.
I am continuing to search but I am not having much luck.
If anyone else is interested, feel free to contact me on Skype. Contact details in my profile.