Bayonet collecting is a very interesting field. Within a short 300 years, the bayonet makers tested just about every edged weapon and tool ever made, and their develoment walks hand in hand with the evolution of modern warfare. In general, the bayonets from the 19th century are the most evolved, while some of the better privately purchased 17 and 18th century examples were aristocratic works of art.
I have a few bayonets listed on my home page. Let me know if any of them look like what you are interested in and I will try to get some more information for you.
http://home.bellsouth.net/p/s/community.dll?ep=87&subpageid=47653&ck=
You can find just about any edge weapons design mounted at the end of a rifle during the 19th century; the global military experimented with roman swords, entrenching shovels, bowies, machetes, epees, and just about everything else. This was back when mass formations were still marching in set piece battlefields, and the infantry line was still trying to deny the ground to mounted calvary. After the US Civil War, the military establishment begins to realize that industrialization and mass mobilization has forever changed the face of battle; as a result we see the bayonet and other edged weapons begin their decline into obsolesecence. By the First World War the bayonets are around 6 inches shorter then they use to be; they shrink yet another 6 inches by the second World War, and yet another 2 inches since then.
The quality is usually good. There were some case hardened military gear which was found to be faulty in the field, but these were fairly notorious and wouldn't survive for very long. Most of them are made from simple carbon tool steel and heat treated for thoughness. The handles were design to sustain very high levels of stress and usually had very large oversized tangs, with brass, wood, alloyed, or pressed leather scales.
It is a very interesting field; especially if you enjoy military history.
n2s