I know you can purchase multiple items at once in NPC stores, but I have found that that is not possible on a regular user's merchant shop.

You probably think, 'Wow, this girl's so lazy she can't even click a few times.' 

But I can prove you wrong. I wanted a very large bulk (such as 30 of the same item all at once) yesterday. As I found a good priced merchant shop to buy from, I found there was no bulk purchases. 

You click 'Purchase'. Then, you click 'Go back to [insert username]'s Merchant Shop.' 

So, speaking techy, I had to click 60 times to get my items. Plus scrolling down or filtering the shop to find it. I don't know if it's just me, but I believe that is a bit too much. 

Don't believe this is an important issue? You try clicking 60 times in a row. (you should do it in the 4 planets to collect creatu eggs)

 Thank you so much for taking the time to read this. :) 

I support your idea. I hope there will be such feature soon.

Meanwhile, this is what I did when I wanted to buk purchase kayoki eggs from a shop. Ctrl + click. I still had to click the same amount as you said (let's say 30 eggs, 30 for eggs and 30 for closing tabs) but it saved me from the trouble to search the egg again.

I usually do the same thing as rescreatunicorn with opening each perchace in another tab.

You can click your back botton also and it will take you back to the same spot in the shop so you dont have to scroll for the egg again.