I think I know what your asking of…. these would be some of the top purchases that have directly contributed to additional success in the field or on water.
Honorable mentions – Mr. Heater, Marcum LX9, Coast to Coast .22LR, my wife and 2 daughters
#10 Sleep Creek DLS #11 & #2 coil traps Incredible holding power and a lot less misses in semi-frozen sets. Some of the best quality traps and longevity!
#9 Tikka Stainless .270 WSM / Boyd thumbhole stock / Burris XTR 4-16×50 scope. I wanted one “perfect” rifle for medium/large game that would cover almost any shot I wanted to take out to 500 yrds. This one exceeds my expectations.
#8 Lowrance Green Box. Back in the late 70’s when the only way to check what was happening beneath the ice was to fish, I rigged up a little folding tripod for the transducer of my green Box and toted it with me on Lake Mendota perch fishing. The first day I ever used it, I learned that perch suspended 20 feet down over 65 fow….From then on, I use electronics religiously to learn what goes on in the water column.
#7 Sage RP III 4wt flyrod blank that I built as a ultra-lite spinning rod. #1 panfish rod I have ever used for the last 25+ years
#6 Dial-up internet service back around 1992- Obviously has been upgraded a few times 
But I knew the growing potential was there for a lot of shared information. Wish I invested a little more $$$ into that thinking 
#5 Lee Melting Pot – I ran into a sweet deal on a melting pot at a garage sale back in about 1979. Since I bought that, I has to get molds…That really was the trigger point for all the DIY rod/tackle stuff that I do.
#4 Loomis IM6 9×9 flyrod. After years of using crap rods (All rods casting,spinning,& flyrods), I learned the true difference in using quality. This one rod truly changed my mindset and had the biggest impact on the quality level of equipment that I buy today.
#3 Koppers Live Target Gizzard Shad 1/2oz 2″ in Pearl/Blue. This one bait has become my “money” bait over the past years. As much as I like Rapala products, I watch them playing catch up in the versatility of this one bait. In lipless, it has the most variety of uses from vertical jigging, ice fishing, ripping through weeds, and species of fish that just inhale it. Now to the point that I burn through about 48 to 60 of these a year!
#2 Hummingbird 1197 the week that they were originally released. Adding this level of technology to my boat allowed me to scan water and confirm/dismiss acres of the water column in just minutes. Not only getting things dialed in; but vastly added more fishing time to my day.
#1. 1991 Yamaha ProV 150 
This one tool has given me THOUSANDS of run-time hours. Countless tournaments, pleasure rides, guiding, and so on. From 100 degrees to in the low 20’s, Mr. Reliability has taken care of me in every condition imaginable, fired up flawlessly, ran smooth, and never cost me a penny over standard maintenance. He’s loosing his compression and I know time is now becoming limited. But over 22 years of HARD use, this motor has gotten me to places that I have enjoyed the most in life! 
Well, there is my top ten…..Thanks for making me think about how much money I have spent over the years 
