Maybe if we slice it this way,
The kit cost $200, you bought $113 worth of parts to put into it to make it usable. You spent 1.5 hours driving around to acquire the parts, at $35 an hour, lets call that $53. Its difficult to calculate car down time since it is a pleasure vehicle, so we'll skip that. We also won't figure installation time since that would be required on any kit, new or used. Since this was a used kit, lets depreciate it 10% annually, for a total cost of $135 for a three year old kit. Add depreciation to your costs so far and you total cost for this so far is $501.
At a new price of $450 plus shipping, lets say $25, total of $475, buying used has cost you an additional $26 plus down time on your car. Now, that isn't to say the new kit would have arrived perfectly complete, although odds are it would have. But, if, by chance, it was missing a single part, like the banjo bleeder, you would have been in the same situation for down time as the used kit. All you would have been lacking is the driving around and acquisition of new parts. But if it did arrive complete, you got it installed without incidence, and were back on the road in two weekends, all you lost was over buying the used kit was opportunity cost of driving your car and $26.
Perhaps you could look at it this way, you were already ripping the back end apart and the effort to experiment has cost you only an additional $26 over simply buying a kit. That's cheap in the car world of experiments.
So while you may be pissed, are you $26 worth of pissed? Principles can be a very nebulas and expensive thing to hold dear and will vary greatly from person to person. I ended up in court over principles once. Very similar situation only the costs were much higher and it had to deal with broken promises and failure to deliver upon those promises. To obtain the satisfaction of upholding my principles, I spent $8000 in attorney, arbitrattion, and magistrate fees. The net results was I got everyone to agree that I was right. Seeking restitution for the agreement that I was right netted me absolutely zero. However, for another $10k in fees, I could have pursued further action of collection with no guarantee of ever recovering any funds. But I still would have been right. Will the defendant in my case think twice before doing that again, I have no idea. Maybe it will sour him on ever offering those services again, maybe not. I'm sure lessons were learned on both sides, as is the case in your situation.
I'm sorry to hear your car is down and its cost you some energy and peace of mind in the process. Once you ahve parts in hand, installed and are back on the road, things will all seem better.
