Fabric depot has two. One is Moda Marble which might be a better choice because if the yellow doesn't match exactly it won't really matter because it is a marble which reads solid anyway. AND it just happens to be on sale.
http://www.fabricdepot.com/index.php...&pageid=157560
If this is too goldy, they have one called Lemon
Here is a link to all their flannels:
http://www.fabricdepot.com/index.php...string=flannel
There is a polka dot one you may wish to consider as it has other bright primary colors that match your Avengers flannel.
Have fun shopping!
Edited to add, Connecting Threads has a yellow on yellow polkadot but I have never used their flannel so can't attest to the quality. You absolutely can not go wrong with Moda. I have also had great luck with AE Nathan and Kaufman flannels too.