That's a good price. It's about $200 less than other reputable sellers. The only issue is delivery. Normally you will need to have your installer there to take the parts from the delivery truck into the garage. The trucking company usually will not offload it for you, but you could call Costco's delivery company to see what their policy is.
Edit: Just saw the delivery info from the link:
Due to the size of this equipment, the carrier will call you to arrange off loading options which may require additional charges. A forklift is required for off loading. If you do not have the means to unload the equipment at delivery, we have several options that can assist you. For delivery options call 877-432-6627.