The estimated cost to replace the trackpad on a late 2009 Macbook (Unibody)?

[Ken Sp.]

Have you looked to see if it is possibly a battery that is swollen. Many times when the batteries have issues, they swell, putting pressure on the trackpad.
If this is the case, sometimes you can activate "touch to tap" and it will accomplish what you need.
I had a friend have there's replaced at an authorized Apple repair facility, and I think it was around $150.