Transit Bus Procurement Act This bill directs the General Services Administration (GSA) to provide access to GSA sources of supply (schedules) for buses to recipients or subrecipients of federal public transportation grant assistance to purchase buses for public transportation. The Department of Transportation shall restrict schedule access to recipients or subrecipients in areas with a population of: less than 200,000, and 200,000 or more with 100 or fewer buses in fixed route service during peak service hours.