Prices estimates below are just for slipcovers labor, not including fabric. 

Parson chair                      $125-$175

Ottoman                             $95-$175

Box cushion                        $45 +up

Pillow                                  $25 +up

Arm covers                       $20/ pair

Rolled armchair            $285- $400

Love seat with 4 removable cushions $435-$550

Wingback chair              $325-$450

Fabric pre-washing and ironing $5 per yard

Chaise lounge - 2 cushions   $ 500

Duvet cover                  $150- $275

Bed skirt                       $175- $275

Curtains $20/width up to 110 inches

Curtains $30/width larger then 110 inches

Average size cushion 2 to 5 sq ft   $65

Large size cushion over 5 sq ft   $75 and up