I've kept tabs this seller for months now; the glassware s/he sells is nice, if you enjoy the uranium glass effect like me.
Usually this seller offers glassware shown in this post of mine. The glassware is authentic in that it is uranium glass, and effects under UV light will show it as such. However, this stuff tends to be circa 1920s; my own set is made by Cambridge and ~1927. So, while these are excellent cocktail glasses, and often (as is the case with my own; which is spot on at 1.5 oz) have etching that can be used as a dosing mark, they can't possibly be "absinthe" glasses; absinthe having been banned a decade prior...thus no manufacturer would have produced them as such. In fact, if I'm not mistaken, all uranium glass was produced during the depression era; which post-dates the ban of absinthe worldwide.
So, if you are looking for glasses like the ones offered by this guy, you are better off just searching for suitable uranium/vaseline glassware. It's fun, particularly neat for blanches, but you won't find an authentic uranium absinthe glass I'd think. Considering how much the seller hauls in for these pieces I'm tempted to sell some myself; having bid against her/him on a couple sets I know the profit that's being reaped here...but I'm just not that motivated really.
If you're interested in having genuine vaseline absinthe glasses, your only option is to have them custom made. Raw vaseline glass cullets can be found on Ebay and elsewhere; and I'm sure that with some per$uasion an artisan glassblower would be able to handle the job. I've considered doing this myself but haven't quite gotten around to it, but I may hit a local renfest when the season rolls around and make inquiries. The only manufacturer still crafting vaseline glassware, that I know of, is Moser Glass; I've already e-mailed them asking about the possibility of them starting a line of absinthe glasses, but I suspect it will take interest from others to motivate them into the attempt.