no point tuning your car 2x times.
i know for tuning safc its like $150-$250, i would guess retuning stock ecu would be more like tuning something like a pfc so you will be looking at $400-$450 (just a guess)
And if you retune your stock ecu then there is no point in getting an safc.
safc is a band-aid , quick fix, retuning stock ecu is just as good as getting a full ecu
Cheers michael