Unfortunately, there is no way to know exactly how much the new iPhone 13 will cost until the official pre-order date. Prices for the previous iPhone 12 ranged from $699-$1599 depending on the model, so it's likely the iPhone 13 will stay within this general range.
However, it is possible to get an idea of how much the new iPhone 13 could cost. Apple typically follows a certain trend of increases with each new model they release, so we can look at past iPhone releases to get an estimate. For example, the iPhone 11 cost $699-$1499 and the iPhone 12 range is $799-$1599, so it's likely the iPhone 13 prices will start from around $799 and go up from there.
In general, prices for the iPhone increase each year, so it's a safe bet that the iPhone 13 will cost more than the iPhone 12. Technological advances such as 5G and upgraded camera capabilities often contribute to the higher price point as well.
It is difficult to give an exact answer to this question, as the final prices for the iPhone 13 won't be announced until Apple begins pre-orders. You can visit this website for updates on the new iPhone 13: https://www.iphoneds.net/iphone-13-release-date/.
