$400 is a very fair price in today's market -- not high, not low. The good ones are going for $500-700. In just average condition they will sell for $350-400.

1950 was the last year of production for the Long Branch from what I understand. Only about 43,500 units were produced, so that was a small number compared to 1943 when LB produced over 350,000 rifles. You will regret not buying it in a year or two.