Why is there such a big price difference for Botox?

I don't usually look into things like this, but lately when I take photos, my jaw looks particularly big, so it's starting to bother me haha.

So I'm looking into Botox, but the prices are really all over the place, so it's confusing. Some places are super cheap, while others are more expensive than I expected.

To be honest, since I've never had Botox before, there are even more things I don't know. Whether it's a difference in the product, the dosage, or if it's due to a promotional event...

A friend of mine said that the refined facial contours lasted for quite a while after just one Botox injection, but I heard that some people's results returned quickly.

I feel like I've read dozens of reviews while searching for Botox, and the more I read, the more conflicted I get lol

I am especially curious about the starting dosage for first-time Botox users, and I would also like to know if there are any cases where getting too much leads to unnatural facial expressions.

If anyone has received Botox, please let me know how satisfied you were. I think I would be satisfied even if the change was just natural, but I am most curious about actual experiences. As someone currently considering Botox, I would appreciate your honest reviews.