I'd be surprised if an independent shop you approach for the first time will agree to replace just the valve seals.
If you do a search on oil level for M103 engines you'll see numerous posts advising to keep the oil level between the min and max levels. These engines consume or leak oil aggressively when filled to the max level. The oil level should stay at the mid level longer than at the max.
My engine leaks at the timing chain cover in front and between the head and block in the rear. The portion of the transmission viewable from the engine compartment is covered with oil. There is no indication that oil consumption is excessive (no smoke, good compression and leakdown, clean plugs). I add 2 quarts between 5000 mile oil changes. Those 2 quarts are going somewhere, but my driveway is clean. Go figure.