The biggest waste of money is buying poor quality reloading equipment. I use RCBS or Hornady dies and they are well worth the money. Both companies are famous for great service if you ever need replacement parts which is very important.
I also use a Dillon D-Terminator powder scale and believe me it is well worth the money.
I measure every load individually and reset the zero on the scale every five loads.
You really can't be too careful.