1991 Nissan Pathfinder price of new exhaust manifolds

1991 Nissan Pathfinder mileage 144,500. What is the usual price one would expect to pay for new exhaust manifolds for the above vehicle? It's the SE-model I've been given a quote by a Nissan dealership of 1280.00 dollars that includes parts and labor. I was wondering is it best to just shop around for or cheaper price or stick with the deal. I have no ideal even as to how important the exhaust manifolds are to a vehicle performance. Please advise.