I'm in the process of buying a house, and recently got back the appraisal. The appraisal amount is fine, but one thing I was curious about was how a basement bedroom/bathroom would affect  the value.

Most of the comparable houses found in the appraisal did not have a basement bedroom or bathroom. However, in making adjustments, they only added $1,000 to the estimated value of my house for that extra bedroom/bathroom.

Is that correct? Do basement bedrooms/bathrooms really only increase value by such a small amount? Is there anything I could do to improve the basement/bathroom so that it would have a larger impact on the house value?