> 4. The cash equivalent of whatever you get paid for one visit to a blood donor clinic (since I believe you get paid for it in the USA).

Well, I don't know how it is in other places, but the local blood bank has 1) a regular office, where I don't know what the reward is, besides the knowledge that you're helping them, and 2) a Bloodmobile that parks in the parking lots of various businesses once in a while when they're holding blood drives, where you get a t-shirt usually proclaiming your donor status and/or encouraging others to do the same, and a coupon for a meal somewhere, to supplement the snack they give you to help you recover.