From my experience and association with other other collectors of world wide reputation it is this.... and I am speaking without reservation, an unguarded comment. If you have the money, you are a millionaire, or better still have no children and are very successful, you can afford to demand perfection in Hauben and Imperial German militaria. You then, can afford to pay the top prices commanded by the "most perfect" pieces. At that level, you biggest concern is not to be taken in by the dealers who see you as a "Cash Cow" who can be fed, so called "rare helmets" which are in fact put together to suck your money out of you. Dealers are businessmen, no matter, militaria, art, antique furniture, watches, jewellery, whatever becomes collectible and worth money where they can make a dollar, they are going to find it, or fake it to sell it to the person they have identified as the guy with the bucks$ That is the problem of the wealthy collector, who becomes identified as such to the dealers....he/she has a target on their back. However, at the same time if a legitimate rare piece comes up, they are going to get first choice at it. First, because they are known to have the money, and second because they have already spent thousands with the dealer. Their self protection, is to become an uber collector and arm themselves with the most knowledge possible, or find an expert whom they can trust to "ok" their purchases, and guarantee that they have not been "burned".
The rest of us, which includes myself from the very beginning of my collection years, have to collect on a limited budget and have to accept less rare pieces, imperfections, missing fittings, cockades, chin straps, spikes, whatever.
Any collector of anything, has to collect according to what they can afford, or what they can charge on their credit card 
Then, there are those of us with limited budgets who decide that they can learn how to restore these helmets and save some money but also earn money by helping other collectors. Consequently, we have myself, who restores for others and charges for my expertise. We also have other members who fix their own helmets for their collections. Everything, is related to individual personality, and individual finances.
The last way in which "the little guy" can save money/make money and add to his/her collection is to follow czechlegion's example..... treasure hunt amongst the masses, and find the stuff.
This is the ultimate thrill...Indianna Jones!! In my 30 year experience, this is how the entire collecting universe works. B