The cash flow of any non-profit comes from direct mail and Avery 5060 labels are the standard. Staples equivalents are every bit as good (and packaged to keep flat and attached) at a little less cost.
I am an Avon representative. These labels work great on my brochures. I put my name phone number and e-mail address. At my regular job I use the same labels for brochures and pamphlets and also as address labels. We have used them to put on water bottles at trade shows as well.
I use these labels for our church newsletter - and glad I discovered them. They are at least 1/3 cheaper than the Avery ones (maybe more) and just as good.