I have an old Adesco safe from the 80s and, of course, I have lost the combination.

The model # is 1406. It's about 12" square, encased in concrete, so it's too heavy to move. I don't mind paying someone to open it but I'm getting quotes from $450 to $800. Does this seem reasonable? I don't know if I left anything in there so it's a bit of a gamble to pay that much to find out. I'm in Ventura county Calif. Any recommendations most appreciated.
Thank you.
Art