As reported the first Android Mobile phone will be unveiled at an event on the 23rd by T-Mobile. The Wall Street Journal reports that their sources tell them that the first Android powered smart phone G1 would sell for $199.
The price is a pretty safe guess since the iPhone 3G sells for the same price and there is no way the Google phone can be more expensive if it wants to have a chance.

T-Mobile is apparently unveiling new aggressively priced data plans with the G1.
The Google brand will be present on the G1 next to the T-Mobile and HTC one.

We know that HTC builds great Windows phones. The big unknown is how well the Android software works and how smooth the UI of the first Android phone is going to be.
More details on the WSJ.