I figure hardware for a string inverter system costs about $1/watt. Rapid shutdown adds some, and microinverters cost a bit more.
His quote was $2.42 per STC watt of panels. Assuming 26% tax credit included, $3.27 per watt.
What is AC wattage rating of microinverters? That, and expected panel wattage under normal conditions, will push cost a bit higher.
I think these prices are in the normal range. Labor and whatnot costs money.
He needs to consider utility rate schedules, how they will be changed the moment he installs solar, what is coming down the regulatory pipeline soon after.
Look at it in terms of payback time and savings. If there are not significant savings vs. buying from utility, don't do it.
Will he want battery backup later? Buy a system supporting the backup (functionality and price) you want.