I ended up taking advantage of a specific cards-only 50 %-off sale that was only offered for a few hours. I just lucked into it while checking the site to learn about regular sales - strange how these online sites do business sometimes. So I feel much more thrifty about my custom-card project now. They were shipped out in less than a day so I am right on schedule or even early.
In the middle of the night (why does that sometimes happen?), a better 66-cent postage option happened in my brain. It suddenly dawned on me to use two of the 33-cent apple stamps. They will look seasonal and are small, simple, matching stamps. Since I didn't want wedding stamps, I was thinking the only choices were the 66-cent black butterfly or adding the extra postage stamp of George Washington, neither of which look the least bit seasonal.
We have a date for the large family party now and it is 11 days earlier than other gift-giving occasions. So my first gift deadline will be 8 (wow) children's gifts and 1 other gift purchased and wrapped in advance of that.