Matt, welcome aboard...
Much of your question will depend on what impression(s) you plan to do, also what your unit had/has or using. Some units have guideline preferences on what model or type of long arm they desire members to have. Many others dont care what model or caliber it is as long as its a three-band military issued musket.
ArmiSport and Euroarms were the two primary makers of reproduction long arms for decades. Unfortunately Euroarms is now gone. Both of these were fairly good weapons, but few if any being made on a large scale are 100 percent correct. Some have tweeked and "defarbed" theirs for a bit more authentic touch. If your planning to be able to do multiple impressions, many will chose a weapon that can fit into more than one impression. Generally speaking... Even though majority of weapons saw at least some use on both sides, some saw longer or more use on a given side. If your doing predominately Federal then three band M1853 Enfield or 1855, 1861, 1863 Springfield generally would be the better fit, depending on your unit. If Confederate, M1853 Enfield, or 1816,1842 Springfield smoothbores, tend to be the general favored preferences. Variations will exist depending on specific unit portrayed and/or date-time and theater. Most tend to determine and chose which given weapon could best cover the most time frame for what they intend to portray.
The days of "inexpensive" muskets are moreso a footnote in history these days. New ones have just about tripled in price in the last 10 years, and used ones while less expensive are still holding a good amount their value to a good degree due to the 150th cycle demand. It might take awhile searching and watching but one can still normally find one from someone exiting the hobby for a decent price.
14th Virginia Infantry Regt Co. A & I
- 106th Penna Vol Co.F
- Pegrams Va Artillery