20 - 40 minutes
My white unibody macbook was having problems with the trackpad. After days of searching the internet, trying software fixes, cleaning, checking battery, etc, nothing worked. I finally decided to go for it and buy a new replacement Trackpad with screws, the #00 Phillips Screwdriver, and the Y1 Tri-wing Screwdriver. Total cost with shipping for everything was $96.00.
It took me less than 30 minutes to remove the old trackpad, clean around it, and install the new trackpad. My old macbook now works like new - well, at least the trackpad does. Follow the MacBook Unibody Model A1342 Trackpad Replacement guide on the ifixit website, and you will have no problems. Super easy to follow and replace.
Take your time, and move slowly. You do not want to do any more damage to your macbook.
I highly recommend buying the Phillips #00 Screwdriver and the Y1 Tri-wing Screwdriver. It is worth it to have the right tools, and you will not damage any of the screws.
Be very careful when removing the wiring ribbons connecting the battery and the trackpad. Break one of these ribbons, and your repair is over until you get a replacement.
I would recommend cleaning around the topcase where the trackpad sits before installing the new one. Dirt, lint, dust, etc trapped here will cause problems for even a brand new trackpad. I cleaned mine with a cotton swab dipped in a little rubbing alcohol.
Don't waste any time trying to repair a faulty trackpad. Just drop $100 with iFixit, and your trackpad will be working like new in 30 minutes. Super easy fix.