Last week I bought only Julianos shrine. Now I am sad I didn't buy the others since the rest of the divines are included this weekends items and I'd like to make a chapel for the 8 divines.
It's not that they are expensive... it's the combination of expense and limited availability. it shuts out people from spending more gold later on.
The 8 sigils, for example. Someone who didn't have the scratch on hand for the first 4 during their limited time will not bother even considering the second 4, even if they had the required gold. Who wants to drop 250k on an incomplete set, with nothing more than a gambler's hope that they might manage to complete the set through buying off other people? The limited nature of the luxury vendor was the obstacle.
I don't know the answer but I would assume they implemented it like the PvP undaunted merchant, which randomly presents items for sale. Sometimes it repeats week to week. But in any case, there is a chance it will come back around in the undaunted vendor case.