I've been able to buy 5-year-old desktop PCs for as little as $50.  

A PC that came with Windows Vista, 7, or 8 should have no difficulty running the new Ubuntu or its derivatives.  Linux Mint Debian Edition (which bypasses the heavy Ubuntu overhead) will be even faster.  A very lightweight distro like Puppy Linux or antiX Linux will run on PCs that are 10+ years old and have no resale value.

On Wed, 06 Nov 2013 13:09:43 -0600
Tom Poe <tompoe at meltel.net> wrote:

> Hello:  Time for me to think about purchasing used desktop that can 
> handle latest linux software.  How old can I go?  Less than $200 price 
> range still reasonable expectation?  Any thoughts appreciated.
> Tom
> 
-- 
Jason Hsu <jhsu802701 at jasonhsu.com>