I can't help you with the value of your truck, but I can share what I paid for mine (1928 National AB Canopy Express). A gentleman played/worked on this truck for 50 years in the Sacramento CA area. He never got it on the road and passed away in 2009.
Last summer (2010), a professional antique vehicle appraiser said the following:
- If the truck was in number one condition, it would be worth $19,500
- As it sits, it's worth $9500
Because I established a good relationship with the family and promised the truck would have a good home with me, they let me purchase it for $7500.
Here's the address of a picture that I posted on this site:
https://vccachat.org/ubbthreads.php/galleries/189099/My_28_AB_Canopy_Express#commentsAll my best, Dean