I have been told that a pro will quote 4 to 6 hours to install @60/hr that's $360.00 plus shop materials ~$20.00.
I replaced mine about four years ago and did not think the job was too difficult. It took a weekend to install.
The advise I received was:
Remove the shims (if any) where the top attaches to the frame.
Start at the back and work forward for a superior fit.
Make the top fit on the tight side; it will relax with time and fit perfectly. As it ages, add the shims back to keep it tight.
You might consider renting an air stapler to do the job. It will make things easier.
Four years later: It still looks great and fits nicely.
Good luck