Agree..powerwash first, then repair, then poly sand, then seal... Use a cheap pump sprayer and get good even coverage. Ive seen pricing as low as $1.50 per sq ft. but we charge depending on how bad it is (sunken, moss-filled wide gaps, dirty)....worst one we did was about $6/sf. Its crazy how many patios and walkways are so F'd up and need so much repair...sometimes its easier/cheaper to just start over and pull it all up to rebuild.
Alternative Landscaping, Inc
St Clair Shores