I don't get the 'toothpick' analogy, because I try to totally eliminate things that I can do without on a dive. But I do get the point around purchasing decisions based on value and risk.
My approach might be a little different because I also have three kids who dive. And, for the most part, I supply all the gear for said activities.
For me a big factor in cost control is standardization. Not going the DIR route (per se), but standardization within 5+ sets of gear that I maintain. I limit the types of gear that we use as much as possible, or is practical.
This also helps me be a little more knowledgeable on specific brand/models, and makes buying used gear purchases smart, instead of random. (usually)
Just a few examples...
-other than my shearwater.. We have DG02 computers that I and all kids use. I have not paid more than $100 for any of the 4 I have, and they all work well for Nitrox diving and as a back-up to my shearwater
-Already mentioned are HOG regs. Decent value, and ability to self service. I also have several Poseidon regs, but am trying to keep my brand/types limited to these two, so spares and parts can be kept to a minimum.
-I have Dive Rite Trans-Pack harnesses for all my kids single-tank rigs. I have purchased them all used of CL. One I got for $35 and it looked brand new. *I did replace each of them with a new wing. ..I guess that was my compromise, and area to spend a little more.
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