As the owner of a 40 watt Sunn Solarus piggy-back amp and 2x12 cabinet myself, I am pulling for you to get your $1500. Mine is maybe in not quite as good a condition as yours, but it's close. Best of luck.
I couldn't & wouldn't ever sell mine regardless of the price. I've owned it since it was purchased new by my parents when I was about 14 yrs. old, so we've been friends for 40 years. Besides, it's a great, clean amp.