Has the rating system changed? I have a memory of being asked to rate the “interaction” with a prospective buyer, even though they never bought it.I am not sure if you're envisioning him rating you without buying it or not, but I believe that was how the ratings worked in the past, which was really crappy. I believe now the seller has to confirm to whom the item ended up being sold to and then both confirmed buyer and seller can rate each other. It's a much better system.
BTW, curiosity got the best of me and I saw the ad. If you want to avoid such instances, I would recommend just saying "price is firm" instead of "lowballing will be ignored." It's more true to what is going on. You didn't ignore the lowballer, and it looks like you want $80. So just be explicit about it and perhaps you can truly ignore all the crappy kijijidiots in the future.
Also, as for the OP, now that they've added “fair negotiation“ to the rating criteria, you kind of have to price above what you want and then come down, if you care about your rating. Pretty annoying, IMO.