I cringe at the reception a thread like this might get, I hope I don't get run off. How about common parts that can substitute rare, expensive or hard to find items even if they're not exact. For example not every mini is worthy of that ultra rare expensive disc caliper. I don't have very good luck searching the forum so apologies in advance if this has been done already. Another idea is how about parts to stay away from for whatever reason? I had a couple of kill switches that should be banned for their poor quality being dangerous.