There's usually some l'heure bleue in edt for the prices you say, but my problem is that these are modern looking bottles. Many of them are certainly pre reformulation, since reformulation was recent, but I don't know how to distinguish pre and post reformulation from pics - so I am myself interested in how to do so if anybody has good suggestions.
Older bottles which are clearly pre-reformulation, like the round "clock" bottle or the "blob" bottle, go for much more than $100. Parfum, whether pre or post (cannot distinguish myself) goes for even more. My only purchase of l'Heure bleue vintage on ebay was once a 1/4 full "clock" bottle, perhaps 10 or 20 ml of perfume, for $25, which turned out to be in very good state. But things like this appear rarely.