What is a good USB keyboard?

I am looking for an USB keyboard, as my laptop’s keyboard broke (a key fell out and might not be replaceable). Criteria are below:

*Must be Windows 7 compatible
*Hopefully, no more than $20 (not counting S&H)
*Durable (would last at least a couple years)

Please help. Thanks.

P.S. Equally useful would be letting me know what USB keyboard not to buy.