I was only comparing the price on Dunlops at the Tire Rack:
Dunlop SP Sport 3000A DSST @ $119 [Summer]
Dunlop SP Sport 5000A DSST @ $137 [All-Season]
I just saw the Goodyears that are sometimes fitted to Coopers:
Goodyear Eagle NCT5 EMT @ $165
The Tire Rack classifies the Goodyears as "Grand Touring Summer" and the Dunlops as "Ultra High Performance".
I don't think tire replacement cost will factor into the dealers decision of whether they'll do a tire swap.
One 16" runflat probably rides like any other