A 7kw Honda generator is more than double. I would venture to guess they are probably 4-5k. That doesn't include a propane kit. Add about 3-4 hundred or that. That would buy about 8 crappy generators.
As far as Costco goes, they are not always the friendliest but I have always been able to return a broken item. I don't care how nice they are. One time I was talking to a asst. manager with a bunch of facial piercings. Every time I started a sentence, he cut me off repeating the same thing to shut me up like I was too stupid to comprehend what was being said. I told him to go ahead and finish EVERY THING he needed to say and tell me when he was done. I then told him that I would rip out one of his piercings if he cut me off again when I spoke. That got the message across. After that I called corporate and filed a complaint.
You want to buy a Honda, go ahead. For 600, I consider this a throw away with a generous return policy.