A lot of the value will stem from the manufacturer. There were many manufactures of 1911s during the war, and these pistols were kept and refurbished through the end of the service life until they were replaced by Berettas. In my arms room in Germany in 1992, we had a lot of Remington-Rands, Ithacas. I would think that these are the most common. If this one says something like "Singer (Sewing machine company)" on the other hand, it is a serious prize.
Do a couple of things. Go to your library and see if they have a few books about collectible firearms. Then go to sites like Gunbroker.com and Auctionarms.com, and do a little digging in the collectibles section. They will have all kinds of hints in the ads about serial number, date of manufacture, documented history, etc. Not reliable information when looking at internet ads, but it gives you an idea what the market looks for.
Remember, that a lot of G.I.s took them home after the war, and this makes them fairly common. Also that the REALLY desireable ones got IDd and sold a long time ago. The REALLY good finds are becoming very rare.