Home and Garden How much does basement finishing system cost? How much does basement finishing system cost? Finishing a basement costs roughly $20,000, but the total price can range from a few thousand dollars to as much as $80,000 depending on the size and style of the space.2021-06-15 Related Posts:Is it worth finishing a basement before selling?How do I stop water coming from my basement after heavy rain?Can you make a room in the basement?The Home DepotCarpet Installation Cost Calculator can be used to calculate the cost to install carpet.