Your M29-2 was built between 1961 and 1979 with an N prefix serial number denoting manufacture between 1969 and 1979.
If your gun is one of the 6500 made with a 4-screw sideplate carrying serial number between S130000 to S167500 it is worth a premium.
Early Model 29's can often fetch a premium over the listed "book" value depending on condition, finish (blue or nickle), barrel length and other features.
Book value on a blued 4" M29-2 revolver with a 3-screw sideplate in excellent condition is $400. A 4-screw sideplate model will bring $600. In VG condition, the disparity narrows to $400 vs. $350. Keep in mind that a collector may pay more for a 4-screw sideplate gun for a collection.
Without seeing the gun it's impossible to determine an accurate value as certain features may make your gun more valuable, especially to a collector. Assuming a 3-screw M29-2 in excellent condition with the accessories you describe, a $500 price tag is a fair price. A collector needing a -2 model for a collection may pay more to obtain a good specimen.
I hope this helps.
