Whoa, been in that predicament!
Of course I left my best man wedding speech preparations until the last week!
I can look back now with happy memories, at what was a once in a life time experience, but at the time I was a total wreck!
To get something down on paper I also searched free best man sample speeches unfortunately most of the free stuff I found was unoriginal and stuffed with tacky cliches. I wasted a lot of time searching through the free stuff but felt that the groom deserved something better.
Luckily I discovered Dan Steven's best man sample speeches . It's not free but about 19/20 dollars (might be more now). I got immediate access to a wealth of different best man sample speeches and toasts which I scanned to see which would best suit my situation. I don't mind admitting that I copied and pasted most and added some jokes and toasts from the jokes section.
The great thing was that I had a solid structure down which I could then personalize and make my own. I added some of my own ammunition - personal stories and situations that I wanted to talk about but didn't know where to fit them in or what to do with before.
The whole best man speech took about 45 minutes to prepare, and in your position I'm sure you'll agree what a relief that is!
I didn't bother to memorize my best man speech - read it off some cards (they shake less than paper).
I was told that the speech sounded very professional, and ame off as quite light hearted and fun.
Most were quite surprised, I'm more of a reserved person.
I have to say I was very happy with the result and my secret help which I kept to myself.
Good luck, hope you give a great speech.