Seattle Tree Preservation will drop off a load for free – but you must take a full truck load, which is about 10 yards. You can call any local arborist and ask to be placed on their list for chips. Be sure they’re from an arborist, not a landscaper, or they could contain invasive weeds or spores (such as horsetail). Good luck!
BTW, if you happen to be in Arbor Heights I might be able to share a load with you…