The stamps pictured in the first post, called Kaleidoscope Flowers, are ALREADY available for purchase at the USPS online store.
Read the description at this link. As you can see they have nothing to do with Islam: store.usps.com.
As for the actual Eid stamp itself: If you are not a Muslim, you're not in the target market anyway. Just like Muslims aren't in the target market for Christmas stamps. I would think that both of those stamps you have to specifically ASK for.
You can see a picture of an Eid stamp in the Hoax-Slayer article I posted above.
The Post office has also been issuing a stamp for that phoney, recently invented Kwanza nonsense since the 1990's as well as a Chinese New Year stamp.
They have also issued a Hannuka stamp almost as long as the Christmas Stamps.
Boycotting the EID stamp is, in my opinion, silly. Why shouldn't a stamp be issued for all the major religious holidays of all the major, real religions which are represented by the US population?