Bearing in mind these factors, professional asphalt driveway sealing can cost $.10 - $.30 per square foot or as much as $.50 - $1.00 per square foot.Doing the job yourself might yield savings of $100 - $200 per 1,000 square feet of driveway.According to the website Do it Yourself or Not, DIY costs for sealing a 20 x 50 foot drive run $80 compared to $240 for professional sealing.© 2015 CostOwl.com.All rights reserved.earing in mind these factors, professional asphalt driveway sealing can cost $.10 - $.30 per square foot or as much as $.50 - $1.00 per square foot.