Approx $2,500 for dealer to do a 2.5 head gaskets in the vehicle.
It can vary. Resurfacing (some dealers do, many don’t), timing components, valve covers, etc. and regional rates demand and staffing vary too. Call and ask they might give you a quote for an “average” headgasket job. That’s a fairly standard job locally speaking and some will give an estimate over the phone
A cheap 98 legacy needing headgaskets can be questionable. If it was overheated bad enough the engine isn’t worth repairing. I’d walk cautiously around blown headgaskets EJ25s now - they’re old, not worth much and more prone to people limping them along and further compromising the lower end bearings.