Some photo examples:
First an example of a wappen from one of those special Regiments with "Napoleonic battle honours"
The wappen is from Pioneer Battalion #10 which fought alongside the British against the French. Note the silver helmet plate which is typical of Pioneer. The wappen colour always matched the tunic buttons.....so PB 10 had silver buttons. The battle honours are always outlined in black paint. In this case PB 10 fought in Spain (Peninsula) and at Waterloo. PB 10 was given this honour on Jan. 24 1899. As to value, if you could find one, they start at approx. $600US
The reverse showing screw posts which indicates that this comes from an older pre 1900 helmet. Note the typical grey patina of 100+ year old solder and how it was "puddled" around the screw posts. These are characteristics that most all originals have...any new shiny solder indicates the piece has been messed with. We can also see that the Napoleonic Bandeau was added on after the plate was stamped pre 1899. It is soldered on in 3 spots. Later bandeau wappen will have the honour stamped into the entire piece.
Grey painted steel Prussian Model 1915 helmet plate. This is the most common of all helmets and wappen. There are tens of thousands of these in N. America. Note the lack of detail and sharp lines. this is a late war stamping where the dies were getting worn out and so we see this lack of clarity.
These steel plates rust in damp conditions. Note: the feet of the loops are most often flattened before soldering.
The second most common helmet and wappen, the Model 1895 Prussian OR's. Made from stamped brass with a "gold wash" applied. FR = Frederich Rex king of Prussia. Motto: With God For King and Fatherland. The Prussian units made up probably 80% of the Imperial Army and thus, their helmets are the most easily found.
Again, grey "puddled solder", loops with flattened feet and note the gauge of the wire loops. Most fakers can't duplicate this gauge of brass wire. They will use thin gauge wire or modern soldered screws. You can also see the splashes of gold wash on the reverse side (sceptre and cross).