What would you pay or what would it cost to have a 41 1/2 x 58 1/2 quilt top quilted on a longarm machine ? I usually quilt by hand in the ditch or outline.

It depends. Many quilters charge by the square inch - yours would be 2427.75 square inches. Most prices I've seen are between 1 cent and 3 cents per square inch. So depending on the quilter you choose and the design you want, you're probably looking between about $25 and $75. Shipping is normally extra, as well as thread and/or batting, if the LAQ supplies them.

Most long arm quilter charge between $60-75 for one that size.

Depending on who you ask that does longarm quilting you'll pay between 1 and 3 cents per square inch.

Around here they charge 40.00 for that size.

it depends on your location/location of the long-arm quilter- different quilters charge different amounts- and location matters.
some charge by the square inch=some charge by the project- check the list of quilters here on the board- find a couple in your neck of the woods contact them and ask what they charge- and what their policies are- and turn around time.