If you want to edit turnip price directly in your save file, the prices information are currently stored starting at the offset 0x412060 in main.dat file (but you need NHSE or other save editor: [1] to decrypt that file before you could make the change, and then after applying changes, [2] use it again to appropriately update checksum for the corresponding section as well as [3] to encrypt back such a file). And below is the cheat code for version 1.1.1 (it also works for version 1.1.1a).
Cheers
[turnip buying at 1 and selling at 990]
04100000 AB20FEB8 00000001
04100000 AB20FEC4 000003DE
04100000 AB20FEC8 000003DE
04100000 AB20FECC 000003DE
04100000 AB20FED0 000003DE
04100000 AB20FED4 000003DE
04100000 AB20FED8 000003DE
04100000 AB20FEDC 000003DE
04100000 AB20FEE0 000003DE
04100000 AB20FEE4 000003DE
04100000 AB20FEE8 000003DE
04100000 AB20FEEC 000003DE
04100000 AB20FEF0 000003DE
do you know how to make a high turnip price in a legit console? Just want friends can benefit from it.