I avoid GAS pretty easily by the application of a simple method I've developed over years as a hobbyist photographer: Be Aware of Non-Optimality. That is, in bearing in mind there is no benefit to the expenditure of resources to obtain equipment that by itself will not meaningfully improve my practice - and too, that having gear I do not use will make me regret its purchase, further diverging from an optimal state - I find myself no longer with the urge to replace a perfectly serviceable DSLR with a mirrorless that may be newer, but is not really all that much better at capturing the exposures I care to make.

I'm probably not explaining it as well as I might, but I am happy nonetheless to say I've found my GAS very reliably cured by BeAN-O.