Last month I went into a local vintage clothing shop and bought myself two pairs of used Levis, a pair of 508s and a pair of 511s. The shop was busy with young hipsters so I did not try them on, trusted my judgement. I'm wearing the 511's now, skinny, I maybe would not have bought them if I had tried them on, skinny jeans on a not quite skinny guy in his 50s maybe look a bit desperate.
Re people saying they would not buy Levis now, what would you buy instead? I've had two pairs of Wrangler cords either go missing in the chaos of my house or I have accidentally given them to an alcoholic friend when I gave him about ten pairs of jeans I was hoping I would not go back up to that size again.
I haven't tried these, but have heard good things from a couple friends:

Cotton Denim
Dearborn Denim is the place to go for top-quality, American made jeans at terrific prices. Click here to shop!
Most of their stuff is stretchy like all the other manufacturers, but they at least do have some 100% cotton jeans, made in USA.
At $75 or so a pop, not cheap, but not ridiculously expensive in my book either. When time to buy again, I'll give them a try.