To late for that trip, but Fred Meyers on 176th sometimes has sand shrimp in the fridge by the fishing stuff. Check them really well before you buy them. They have a problem with keeping fresh bait well........fresh, LOL
I do the smell test when I open their fridge, if it stinks I shut it.
The gas station/store on the corner of hwy 161 and the Mckenna cutoff road has them sometimes as well.
The gas station at the hwy 161 and Kapowsin road, might have some. they usually have good nightcrawlers.