I've already run into three instances where Ian has asked for items that are rare (some down to roughly five available) in user shots and cost upwards of 1mil sP. I can't imagine this is intentional.
The one I just ran into was Mini Mango Lolly Ornament. Edit: I also just ran into its recolor, Mini Cherry Lolly Ornament, which only has four left and those last two are steep.

I had one quest asking for a sticker which wasn't even for sale in player shops. These quests really do need tweaking.
This isn't a glitch -- it's largely an inflation issue, which the staff has been trying to work on. Some quests just aren't going to be doable or ideal, regardless. It's all a bit of the luck of the draw. Quest givers can ask for expensive items or items which have been bought out or newly-released and not available in usershops yet.