He has just asked me for a Barnacle-Encrusted Whale Beanbag, that costs on user shops 3.2m It's the first time that I have to quit a WQ O_O I thought that he had a cap for that? Can it be done that he doesn't ask for items that restock on that shop, please?

That item has a normal rarity, so it is within any quest limitations. You can also be rewarded items from Freyalise.

Skipping one or two quests a day isn't a big enough deal for staff to code around, especially since the shop isn't open long at all.

This happens with all new items, no matter where they stock.

Not all the items that stock at Freyalise are super inflated, either. Many items that came out in previous years are pretty reasonable for their rarity.