Value of a rare pistol

Does anyone have a good idea where to find the value of a Colt Model 1911 22 cal. on a 45 cal. frame?
It was presented to my grandfather in LeMannes France after he had won the world marksman championship, the sierial number is 66, after his army division ( the 66th field
Artillery )

very hard one to value ,,because theres no books with special editions firearms and there were soo many individual awards the book would be to hard to keep updated ,,something like this usually has more sentimental value than money value,,if your looking to sell it then your best bet would be at an online auction,,mabey start it at 1000 and see where it goes ,,if you want put a reserve on it of say 1500-2000 ,,i would say somewhere between 1000-2000 would be an ok price if you really want to sell it ,,a good auction site would be gunbrokers.com,,mabey see if you can find something there thats simular and see what the going price might be ..but it's just too hard to give exact values for something thats a 1 of a kind item,,
bigcurt