I have been slowly putting this together for the last month. I found the vintage calf skin tambourine in a flea market, as well as the spoon that I hammered flat for the tailpiece. The nut and bridge are some kind of hardwood (maybe red oak) that came as an insert in the first cigar box guitar that I built. I've used that chunk of wood for all three instrument bridges, slicing it up on my table saw.
The neck and dowel are just big box store poplar 1x2s, laminated. The friction tuners are from cbgitty.com and the Aquila nylgut strings are an Amazon purchase, grocery store generic sanded toothpicks for the frets. The whole thing had a coat of Danish oil upon assembly.
New, decent production banjoleles go for $200 and up. I built this one for about $25-30.