Is there any way to, through The contract, get the Aeter price un USD? I think that I can use an Oracle yo do this, but there is not a simple way of doing this?
The only way to access “the outside world” (which is needed to know the value of AE in USD) is through oracles - so no there is no other way.
I provided an example for this use-case here: https://github.com/thepiwo/ae-oracle-pricefeed
with oracles you can connect anything, relying on the trusted oracle assumption