In real world in terms of buying I have been getting between the mid and 20% below the mid, excellent executions. Expect exiting will be the same. This is over 10 trades or so. So am now a fan of SPX over the SPY options, maybe better executions despite wider quotes and better comms and better taxes. CheersAlthough some quotes may be wide in the SPX, the "real" markets are usually very tight, especially with spreads.
I don't know what I am paying on SPX but the zero comms brokers are the way to go. TDA or IBKR. Single names are running $0.65 all-in on TDA.
I trade SPX at TDA and I'm paying $1.25 all-in per side (commish + misc fees + reg fee).