Reccomendations for sn EASY to use External back up drive

I want to buy my inlaws a easy to use external back up drive that can be easily set up to back up automatically every week or so and switched out with another exact sized drive every month or so, to be stored off site.

While they have a high capacity they have never come close to 500 MB. 

I like WD products and the ease of use, but is there anything that  I should be extra mindful about when buying for not so tech savvy users? Besides the usual stores, is there a place that has good prices on WD products?

Hello,

You can use the WD Passport or the WD My Book to set the automatic backup. You will be able to schedule the backup any day of the week.

WD Passport

http://support.wd.com/product/install.asp?groupid=218&lang=en

WD My Book

http://support.wd.com/product/install.asp?groupid=132&lang=en