I bought one of those cheap, plastic Halloween flintlocks (~5 USD). Here is a fantastic 'ible on painting flintlocks and guns in general: https://www.instructables.com/id/Steampunk-Pirate-Gun-Mod/.
I spent around 15 USD on the plexiglass sheet. It's sturdy and with the flintlock providing structure, it's got some heft. I wouldn't try to hit anybody with it. I used a purple LED from radioshack, which came in a pack of two and was about 3 USD. I only used on LED because I had already used the other for a different project.
P.S. Please excuse the mess. :P