Funny, I emailed the guy last night. I got a reply today.
This is the email I sent.
"Hi there, I came across your auction today and I have a few questions if you don't mind.
Do you make these tanks yourself? If so, can you get them in a bigger size? I would be interested in purchasing at least one and most probably more if I could get it in a 1 gallon or bigger. I really am not sure 1/2 gallon is big enough for any fish.
I am kinda concerned about the size of the hole in the top too. I would be much more comfortable if the hole was at least 1/2 the size of the top of the tank. I prefer to catch my bettas in my hands when I am changing their water, and I am pretty sure my hand won't fit in there

I also change my water really frequently, like 2 times a week, I wouldn't want to stress my babies out by pouring them through a hole if you know what I mean.
I really hope you make these yourself, so that it may be possible to make these modifications.
Thanks so much and I am looking forward to hearing from you,
Fish Enthusiast (especially bettas!)
He does not make the tanks himself. He gets them from somewhere else. I am going to email him again and ask where he gets the tanks from so that I may contact the manufacturer. Also, his reply was very polite, however short it was.
Just goes to show what a little bit of compassion will get you.