I have a pre-model 30 (made before 1957). As well as several I frame 32 hand ejectors. The most I paid was for the pre-30, cost me 225, and was in excellent condition.
The SCSW lists the 30-1 as made from 1961 to 1976 and is worth 250 in excellent condition. This book was published in 2001 and is a little low on some of the prices. I do not believe that 300 is excessive, especially if it includes the original box.
The -1 is when J frame production began, previously it was built on an I frame.
hth
Fred