Easiest inventory management solution for a non-profit?

I work with a non-profit that needs an inexpensive inventory solution. Essentially, we would like to have a handheld scanner that can scan items with bar codes or something similar on them. We would also need a program that could download that info, and allow us to keep track of how many packages go in and out. There is no money involved, so it’s really just a matter of keeping a count of what is going in and what is going out. Can any suggest a good solution? Thanks in advance.

You can get smart phone apps that do this. A friend was looking to develop one and discovered it is already a mature market.

I know they have apps, but its a fairly high volume of stuff, and I worry it will be too slow. Do you know of any that are as fast and reliable as a supermarket scanner (for example) would be?