I have many.
The local American Red Cross donation center recently mentioned that they are phasing out the pins but that there was still a supply of them in the pipeline so they would hand them out until they were gone. But that information is about a year old (I'm currently on a malaria-risk year-long deferral because I went to India) and the Red Cross does change their minds on things periodically, so pins may still be available.
You should get one for each gallon, and each one has a different little number in the center, so you'll get a 1-gallon pin, a 2-gallon pin, etc. So the number makes them all a little different.
If you don't get one for a particular gallon and ask them about it and they have one, they're usually happy to replace or make your collection complete.
Platelet donations, even though they take a lot longer than regular blood donations and are arguably more valuable to the Red Cross, count the same. Each platelet donation or whole blood donation counts as one visit, and eight visits equals a gallon. This is true whether the platelet donation results in a single, double, or triple unit. Also a visit counts even if something goes wrong during the donation and they don't get a product. But a visit doesn't count if for some reason you get deferred (low iron, or whatever). Basically, if a needle goes in your arm, you get credit.
Platelet donors, though, can rack up more gallons per year because you can give platelets nearly every other week, whereas whole blood is generally once every 8 weeks. I personally think people should donate where most needed - for me they like my platelets as I am A+, CMV-negative, and over 200 pounds. For my oldest son, who is about 120 pounds, O-, CMV negative, they really want him to donate whole blood.
