AMD is withdrawing old Durons and Athlons
As of today, AMD does not deliver Durons below 700MHz or Athlons below 850MHz to computer dealers. This means that with immediate effect only CPUs that are already on the market will be sold.
Thus, the product range for the Duron is shrinking to a 700 and 750MHz variant and for the Athlon to models between 850 and 1,100 MHz. So if you want to get a cheap new CPU that also offers good performance, you should definitely take a look at these discontinued models.