Machinery's Handbook; which edeition?

I am preparing to purchase a Machinery's Handbook, and have found a zillion of them on e-bay after finding out the Enco people don't carry it anymore. Seems one can be had at pretty reasonable cost, but which one to buy? I saw the mechanical engineering version, the drafing version, and various editions ranging from pretty early (1930's; maybe 9th) to fairly recent (25th). Is there a standard "machinists" edition? If so, how is this recognized? Is one edition more desirable than another (from a useful information perspective rather than a collector, or whatever, standpoint)? As with most things, I thought this would be a simple "point and shoot" operation; I'm finding that I don't even know what the questions are!!

I noticed that Border's book carries the newest (27th) edition in both the large print and "toolbox" versions, $99 and $85 respectively. They have them in stock at the store near my house.

I have a large print copy at work and home. It is worth the few extra $$'s to have.

The most desirable edition depends upon one's needs.

I have a need to refer to unusual gearing relationships, for which the logarithmic method, contained in older editions, only, is essential.

I am a wet-behind-the-ears amateur who likes to build stuff in the basement. I recently posted a question regarding v-belt pulley dimensions on this site, and one of the many very helpful members posted a thorough answer which was obtained from Machinery's Handbook. Which was the final motivation to start looking for one. For someone like me, what's the best choice? Do th older versions have other essential info such as gear relationships that newer ones don't? My lathe is a 1942 model, but I also have a mill (which I haven't gotten running yet) which is from the late 70's, so getting a book applicable to a particular era doesn't seem logical, unless one particular era's version would be better suited to someone just learning about machining.

Check this old post, seems most feel that an older used edition is the way to go.

http://www.practicalmachinist.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=1;t=009421

Thanks KrisG! The old post had a link to bookfinders.com, where I bought a 1944 edition for $10! Very pleased, as I was watching several on ebay and was prepared to spend 4x that much, and think I'd gotten a smokin' deal (!). Now, if I find I'm disappointed in it I won't feel too bad about it. In fact, even though I haven't ever cracked the cover of one, I'll bet there's 10 bucks of information in there.