There are quite a few issues multiplying apps on the app store itself. So I'd save that for a time when you have some very precise discovery to do.

My recommended growth hack strictly for a short-term test is to price the app on the store at the lowest figure you want to test, while naming a range of prices in the FB ad set.

Your data is going to come from the FB ad clicks, and conversions in the app store are going to be unreliable as whatever price was shown on the ad, the user is going to see the fixed price.

This method lets you test multiple prices very easily, and if your budget allows for a reasonable volume you can even do a little covariant analysis to estimate the value of top features.