The first time I replaced the hard drive on an iMac, I reasoned that it was a one time event. In true MacGyver fashion I was able to remove the glass with duck tape and a spudger. Another friend experienced a hard drive failure and I found myself mashing modeling clay at several points on the front of the glass and gently lifting it away. It was effective, but not at all pretty. I went to ifixit and purchased the suction cups (for less than the cost of the screen cleaner). Next time I will be ready!
I used the ifixit guides (sans suction cup instructions) for the hard drive replacements on a 20.5 and 24 inch iMac. They were detailed, and gave me everything I needed to know to dive in and complete the task.
Spring for the right tools. Just because you can use other "tools" does not mean they will perform as well. I did bend one pin on the 20.5 screen when the duck tape released mid-removal. Thanks ifixit!