$1,400 is the highest I would go for any pre-loved City. I have been looking on ebay for awhile. Several HG color Cities were sold recently for $1,000-1,300. Unless you really need it right away, I wouldn't suggest going higher than that.
I would probably be happy with getting an amethyst RH city for $1000-1200 but the $1300-1500 ones seem like too much, even for mint condition. Especially since sometimes the bags aren't really as mint as some sellers say...
But I understand where you're coming from, I did just put a BC day on layaway that was $1275! I guess I just got lucky with my part times that were both authentic and only needed a bit of tlc for under $1000!