Who's leg do i gotta hump to get a well made 5 speed rear cassette? I don't need 8, 9, or 10 gears on my back wheel...i just want to build up a simple ten speed, without robbing old, rusty parts off of the broke down beater in my garage. Is there any company who makes a decent one still?

https://www.universalcycles.com/shop...&category=1665

Not sure about 5 speed cassettes, but 5 speed freewheels are available.

I think Sun still makes them. Rivendell (www.rivbike.com) had them in the catalog a year or two ago. Not sure if they're still there.
Now that I think of it, was there ever a five-speed cassette? I think maybe the world had changed to six or even seven before cassettes came along, and what Riv had was five-speed freewheels.
You might also check Loose screws in Oregon (loosescrews.com, I think). And in a pinch, check thrift shops. Around here you can get a complete, running, fairly decent old bike for $25-$50. I've cannibalized many a Salvation Army frame building beaters and commuters for the family.

Good luck finding a 5 speed cassette. Plenty of 5 speed freewheels available though. Just add a freewheel hub and you're good to go.

I used to have a Schwinn ( don't remember the model) that was a 5 speed, just a single crank in front. Half of the old 10 speed!

If it's a freehub, get a 7 or 8 speed cassette and toss the extra cogs.

Hammer out the assembly pins, if necessary (or you might have to grind them a bit if they're peened in place), pick the cogs you want and use extra spacers.

If it's not a freehub, Shimano 5 speed freewheels are dirt cheap and everywhere.