Even if it's just the seals, your looking at a lot of money for the job, and to go all the way and remove a head and just replace the seals seems a little short sighted. Better to just spend the extra money for the valve grind and have it all done at the same time while the top end of the motor is off and apart. There is a way to replace seals with the head still on the car, but I've never used it or seen it done. Once you remove the valve keepers and springs, there's nothing to prevent the valve itself from falling down into the cylinder bore. There are attachments for the spark plug port that will pump compressed air into the cylinder and keep the valves up while you replace springs and seals, but if the air compressor or power fails you're SOL, the whole head has to then come off to get it out. It's pretty feasable to do the job yourself by this method since your not pulling the head, provided you have a compressor and all the rest. Never done it myself on this car though, so if someone has knowledge to the contrary please correct me (special tools needed, pressed in fittings, etc.).

I would have the problem looked at by a good indie though, have them do a leakdown test and all that. I'd be surprised if it was just valve seals that had been compromised. Only 145K and it's buring that much oil says two things to me, the previous owner (or owners) beat the hell out of the car and/or they never changed the oil. Either way, trying to sell a car that's burning a quart every 600 miles or so is gonna be tough.