Roadmaster Festival Series Amp

[Bakeacake08]

I have a Festival series amp that I am planning on selling, but I'm not sure how much it is worth. The only postings I found online were for a $350 broken one and one that sold on eBay for $900. From what I can gather from the serial number it was made in '74, and I know it's the one with a SS pre-amp and tube power amp. Any help I could get with determining a fair value will be greatly appreciated!