kenward1 I think the prices are higher in Tukwilla due to it’s proximity to the airport.
That’s a good assumption, and probably has some truth to it, though I think there are some other factors.. I was in Burien today not far from the airport, and saw a $5.39 cash price for one station. I think most people get to SeaTac from the east (I-5, I405) and not from the west (509) so the rentals are much more likely to be filled up in Tukvilla than in Burien, even though some areas of the latter are physically closer.
In any case, yesterday it was $5.199/5.299 for the two nearby ARCOs, but by this afternoon one was up to $5.299/$5.399.