The Nokia Lumia 610 is said to be the cheapest Windows Tango Phone launched till date and this fact is suported by the latest info that was taken by WPBench app. If we are to believe this info, the Lumia 610 will run the build 8757 of Windows Phone 7.5. This is a totally different branch from the current 8107 that is being offered to the public at present.
To our bad, it is possible that this info WPBench might be fake. Thus, there isn’t any cent-percent confirmation as of now.