when should i stop putting $ into it, now at 209k miles?

That is a difficult call to make here online .. It really depends on condition of the vehicle otherwise. One can afford to repair a vehicle as opposed to trading or purchasing another - that is as long as said repairs do not exceed the value of the vehicle..

It really could be the pully or a serpentine belt. Bring it to Melvin's Tire on Belair Rd, Nottingham. 410-661-3900. We will check it and give you an estimate.