fs I am so sorry you feel so angry and ripped off, but I am impressed with your craft and the passion you feel for it, cabinet making is a beautiful art and is becoming rare, I have often wanted to learn it myself.
I make wedding cakes (you can laugh if you want to) but I charge $1000 ++++ and I am booked out. If someone does not pay I feel exactly the same way for exactly the same reasons as you do, espcially when they are friends and don't value how incredible my work is (where as other do). So instead of wasting any energy I just contact a debt collection agency, they take 10% of the collection and chase the bill for me, I have never not had it paid and I don't have to loose sleep just a couple of hundred bucks. There are loads of debt collection agencies and they should use the law and not a baseball bat. If its a cash deal its more difficult, but I would still recommend using a third party, preferably a really calm, assertive one (I use my very scary Irish bookkeeper) b/c if they view you as a friend they just keep screwing you around where as bringing in a third party a) changes the dynamic b) scares them a bit c) allows them to perhaps neogtiate paying it off in installments (you just want you money right)
Your sobriety is more important than anything and sometimes when we make something beautiful with our heart and our hands it is just like throwing pearls before swine....its hurts, but its not worth it, they just don't get it. You just need to get paid....good luck with it and thank you for your post I really do get it!