While I think you have the right idea, just looking at it wrong, equipment last much longer than it's warranty period, if properly cared for. and frankly if I were you I would move to Peavey their warranty is 5 years on their amps and you never have to use it LOL.
The newest gear I am running right now is 5 years old, the oldest is +20 years old. That is not to say I am not looking to buy another system but that is exactly what it is "another system"
I use Shure wireless mics which I rotate in and out of service when they are out of service I pack them up and send them off to shure to be refurbished it cost me $117 per unit and they come back working and looking like brand new, out of 16 Shure wireless I always have 4 sitting after repairs and on average just have four done per year so we are talking about less than $500 for mics per year (but that goes into the taxes as repairs not purchases)
Purchase a decent dependable mixer and you have a mixer that will last at least 10 years but should last 20 if cared for and cleaned on a regular basis.
Speakers well what can I say I have a set of SP4s and SP118s that have been with me since I was 23 years old (how old does that make them, oops damn that is old) but they were well cared for, they have always been powered correctly and have never had a speaker replaced! Yes I have newer speakers because I simply don't like carrying those monsters anymore than I have too. But even those units are at a minimum of 5 years old some over 10. They still look, sound and function like new.
So why resell something that can continue to make you money for many more years? It is already paid for!