What has been your costliest mistake in this hobby?

I asked Stereo Fixers in Boca Raton and Music Technology in VA to "fix" the channel imbalance in my Luxman CL-32 pre-amp.  They BOTH charged me a ton of money and "couldn't fix the problem."

When I had my shop, if we could NOT fix something, we charged the customer the $20.00 "look-at" fee and nothing else.

I guess times have changed with shops now charging lots of money for what they CAN NOT do.

If I took my car to a shop and they could not fix it, I would never pay them, nor would they charge me other than a minimum "look-at" fee in my experience.  

Cheers!

Lol great idea for a thread!

For me, impulsively buying speakers before I realized that I shouldn't be "collecting" them.  

Back in the day, bought a PS Audio 200C, money thrown away. 

Audioquest cables (great product.......but)

OR

Now using Mogami, Canare, or Gotham from worlds best cables
for interconnects and speakers.
14 gauge power cords into a dedicated breaker and hospital grade outlets.
Power conditioners

......same cost
Found this out the hard way.

Getting married.