Is this a good price for an in-app purchase?

Hi,

Firstly please don’t consider this spam or me trying to plug anything.

I wan’t your opinion on weather the price I’m charging for my app’s IAP is acceptable or not.

The price will turn out to about $4.50 USD, and it unlocks calculating force for n-charges (as will be demoed in the following video) and removes ads. The ad version only permits 2-charge.

The video is in spanish (only words), but it gets the point across.

Video:

Please advise if $4.50 USD is too high, low, ok or other.

It should be noted that this app is meant primarily for students.

Thanks.