If you make a deal to purchase something from someone on Priuschat and they said they would include in an extra item (the ones you purchased 4 of, so with the extra there would be 5), so you are expecting it to come in the package, right? The package arrives and, lo and behold, no extra! On contacting them, they say the extra was broken so they chose not to send it. No big deal or do you think they should have had the courtesy to inform you that the item in question was not going to be shipped? Do you feel they should compensate you for the missing item (approximate value $10-$15) since they failed to inform you?
Expecting sometime for free, I wouldn't expect much. Nice thought. As a minimum, "they" should have informed you without having to ask.
If you did not pay for it, why would you expect a to be compensated? As long as the other 4 live up to the sellers description you got what you paid for.
If there was a contract that includes the "gift" or bonus item, you are legally entitled to the gift and if you cannot get the gift, you are entitled to the market value of the gift to be taken off of the contract. However, as a human and moral person? Just let it go. It was something someone was doing as a favour. The law is there so that companies can't say "buy 4 widgets and get a new tv" and then say, "we're out of TV's sorry". If someone promised to give me a plate of cookies for my birthday and then drops a cookie presenting the plate to me I am not going to tell them to make me a new cookie because they promised me a full tray.
If I was a seller and knew you were expecting 5 items, and one broke "Extra or Not", I would of contacted you and informed you of this reality before continuing with the deal. Seems like a reasonable courtesy to expect. That being said, on a 10-15 dollar item that was being included as an extra, I wouldn't escalate the conflict. You got what you purchased,- just not the "extra". Part and parcel of personal internet commerce. If this isn't a company, or manufacturer, expecting a private individual to compensate you, for something they were throwing in for free? Well I just wouldn't do it. Neither would I purchase from this person in the future. I would say there is a big difference. OP say's the purchase is from "someone on Prius Chat" which makes it seem like a private party transaction. In which case I would of liked the courtesy of being informed the "extra" wasn't going to be sent. But if it didn't work out- I don't care. If this was a company, or manufacturer running a "free extra" offer? THEN I'd want to be compensated. That's the etiquette in response, I would follow.
worst case scenario you can always buy new and pay retail . that way you'll know exactly what your getting and if there is a discrepancy you will have a valid argument