It has been suggested multiple times, though i do not see the difficulty in installing one. Maybe it might be added one day, who knows.
I Have supported the idea in the past, and i still do so. Would have been nice to see an older topic bumped though.
He is not asking about the amount of gold required for a successful amplification. He is asking for the cost per attempt.
at least that is what i understood.
226 gold for +9 > +10 attempt. lvl19 arena 1h axe. That is all i can help you with currently.
A Confirmation "yes" or "no" button after selection would help a lot with mshop pop-ups.
Even with amplifications when you hit the non secured amplification button ( happens when you run out of signs ).
Unfortunately not.
But there is suggestion topics in the suggestions section of forum that suggest other methods. Perhaps you may wish to include your thoughts upon such a topic.