1937 Nazi Germany Hitler Stamp Souvenir Sheet

I bought this 1937 Souvenir Sheet from E-bay for 11 usd plus 3 usd shipping.  It's from Nazi Germany and it has originally issued for Hitlers birthday on 5th April 1937 but used for various cancellations throughout the year 1937. One I bought has 20th April 1937 Berlin cancellation seal. This sheet has the inscription "WER EIN VOLK RETTEN WILL / KANN NUR HEROISCH DENKEN", which means "He who wants to save his people must think heroically".

Well it's not something expensive and catalog price would be around $20. Worth nothing unless it's in super fine condition. I have just won the auction and image is form ebay. I hope the condition of sheet is same as in the image because sometimes people Photoshop to make these stamps look better. Even thought it's not a rare stamp It's important to me because it will be my first Nazi Germany stamp. I have had a huge interest in everything related to World War 2 so It's same for stamps and coins too.

I found loads and loads of stamps related to world war 2 and stamps from that time for cheap in ebay but I can't jump in and buy all. But I think I will start a collection of stamps from world war 2 times, belongs to various a countries like Nazi Germany, Imperial Japan, Soviet Union. Also German occupation stamps. It seems Japanese war time stamps are more rare than Germany. I couldn't find many in Ebay.

I have no experience or knowledge about these War time stamps so I need to do more research about those. I was told Serious German stamp collectors are notoriously picky about the condition of stamps so any stamp with any kind of damage or look bad might worth nothing at all. Collecting stamps like this is kinda very expensive hobby. I need to earn more money! :D