I would like to know how much it cost to get married in Boone Iowa Court house??

It costs $35 for a license. Not sure how much to have the marriage performed, but this site has a number to call them
Boone County Marriage License, Boone, IA (http://usmarriagelaws.com/search/united_states/iowa/marriage_licenses/boone_county_recorder.shtml)

Normally you will make an appointment with the judge to do a wedding in chambers ( his office) without doing a web search, the cost is normally about 100 dollars.