http://qui.live.mediaspanonlinen.com/rss/ Quincy Herald Whig en-us By STEVE EIGHINGERHerald-Whig Staff Writer Gas prices in Quincy have fallen to the $2 mark for the first time in about 25 months, a stark contrast to the record $4.21 city residents were paying in mid-July. The record price for diesel was $4.90 in late July. Prices at the pump are even cheaper across the Mississippi River. Missouri has the nation's lowest average per gallon numbers at $1.79, according to the www.fuelgaugereport.com and www.gasbuddy.com Web sites. Gas in West Quincy, Mo., was selling for $1.89 on Monday. Illinois ranks 26th with a $2.09 average per gallon of gasoline. Diesel is averaging $3.10. http://qui.live.mediaspanonline.com/new_story/Gas-Prices--TUES