ameraucanas aren't really that rare, but it is a little tricky to make sure you get a true one and not an EE.....
i've seen them in both bantam and large fowl size....
i just got golden phoenix and they look like that too... there are a few breeds that have racing stripes on the chicks... in fact, my partridge silkies had psuedo stripes....
and i wouldn't say most bantams look like that either... i have about 20 bantams chicks in my bathroom right now, and not a single one has racing stripes... i do however have another large fowl EE chick or two that look like that.. i need to quit hatching them.. lol...
but as far as your colored egg layer type, assume you have an EE.... the county fair out here had about 20 entries labeled Araucana or Ameraucana or some variation of the spellings, and having done a LOT of research on true Araucana, which leads you to learn the Ameraucanas, i can tell you not a singe one of those birds was true and no where near show standards... lol... but that's what happens when people who don't research get birds labeled something... then breed them and sell the chicks as something they are not and it spreads from there....
when i bought my EE, they were labeled Araucana..... i knew that was one of the breeds with the blue egg gene so i got 7 and brought them home.... got online and started looking and reading more, and within an hour i knew what i had wasn't what i was told i had... but no matter, i just wanted the pretty eggs... out of the 7, 1 was a roo, 2 lay a terracotta pinky egg, 1 lays a very nice blue, and 3 lay greens....