It gets Hard sometimes. There are a lot of fake things floating around. Occasionally it gets hard to tell which from WW 2 are fake and which ones are real.
Reliable Sources
You will find one or 2 Reliable sellers online. I wouldn't spend too long looking around for different people since there are a lot of misleading advertisements. Places such as eBay and CraigsList do have some incredibly misleading ads, so be mindful.
Building Up Your Collection
I Can't stress this point enough. You don't have to spend all of your money and time attempting to get everything having to do with WW2. You may end up with a big colelction that amounts to next to nothing. You need to focus your efforts on specific products. You will find 100s of belts and cloths you can purchase from that period that sell for under $100.
I'm collector myself, maybe not Of WW2, but of different things. You are feeling the need to purchase everything that person did. You should focus on rare and harder to find things. These can be worth more money down the road.
Areas of Interest
Collectors have their Areas of interest. You need to focus on what interests you more. You may come across a distinct general more interesting than others. Focus on that general and buy items related to him or her.
It's very similar to Being interest in a couple of pop artists over others. You purchase up items Related to them. Collecting rare things is about more than just the main point. You should have some kind of emotional connection to the time period also. Your Collection should have some heart behind it. Like [http://www.cosl.com.sg/UserProfile/tabid/61/userId/12294401/Default.aspx take a look at the site here].