Made in 1940. Value will depend on factors you don't describe; overall condition, barrel length, accessories, original papers, original box, whether the ivory is in fact ivory, if it is ivory whether it was factory supplied or aftermarket. Range from a few hundred to a few thousand. BTW, the only way to know if the ivory is factory is to get it lettered by Colt. The Colt website has a section that describes how to do this. Cost will be in the 100-200 USD range.
You can get faux ivory grips for a Colt Walker at: tombstonegrips.com
$1500 -$1600 without Ivory grips,,, the grips would need evaluation.
Try Nutmegsports.com
About $400, new
Try asking Jim Alaimo of Nutmegsports.com
Although often billed as ivory or bone, both sets are synthetic. Frisch verified that all of these grips were made by Maurice D. Scarlac of a material he developed called Catalin. Wayne reportedly liked them so much that he took them home and personally "tea-stained" them to a yellow color such as the patina often seen on ivory and bone grips.
No serial number provided.
100-300 or so
Give you $20 for them. Thanks, Atson
Faux ivory doesn't tea stain. You can antique it by applying burnt umber paint, leaving it set for a few seconds, and wiping it off with a soft cloth. Continue the applications until you reach the desired shade.
Way to little information. What kind of Colt Revolver? Single Action Army? Python? Diamondback? What condition is it in? A set of new ivory grips with a steer head would set you back 800 or so.
50-1500 USD or so depending on specifics