OK, I think I've finally decided to take the plunge and get a Class III arm. I've got my eye on a STEN because of some geneological research I've been doing - turns out I have a relative who was involved in its design.
All that said, what should one look for? MKIII the best way to go? What's a fair price? If you have one registered receiver, can you have as many parts kits as you want?