Depends on how much you want to spend. Ebay, places that sell of old industrial equipment or absoluteclarity.com are a few places to try.
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Here is one just like mine.
http://cgi.ebay.com/30X-ILLUMINATED-...QQcmdZViewItem
Quite old looking but probably still better than 99% of handhelds and will give you a much more 3d view.
http://cgi.ebay.com/Unique-Bausch-Lo...QQcmdZViewItem
Or one like mine (slightly different stand and mine came with extra occulars, light etc.)
http://cgi.ebay.com/Bausch-Lomb-Ster...QQcmdZViewItem
Or something cheap like
http://cgi.ebay.co.uk/Microscope-Ste...QQcmdZViewItem
Don't know if they are up to much but again probably better than cheap handhelds.
And another B&L sz but only at around $40 with a few hours left.
http://cgi.ebay.co.uk/Bausch-Lomb-St...QQcmdZViewItem
I use a 10x loupe, an OptiVisor with several different magnifications, a Radio Shack lighted magnifier (about $15), binocular microscopes (now own three), an illuminated magnifier on an articulated arm attached to the bench, and the latest is a video magnifier which really magnifies well, lights up the stone, and shows it on a TV Screen. I use all of this in my quest to better understand what is going on at the edge. Do you need all of this to hone a razor? No, but it will better inform your honing.
I use a 40x microscope that will go to 80x. Picked it up on ebay. The 40 seems to be perfect. I also have a jewelers loupe and the little Radio Shack pocket microscope, but they both make me dizzy (not that I'm not already) when I look through them for any time.
Lynn