My approach is simple. I upgrade the cartridge last. For as long as I hear improvements while upgrading other elements of the chain I will not touch it. So, trust your hearing, be nice to your wallet and stay cool. When the time to upgrade comes, I will have a small problem because you can't buy them try them and return. Either I will do it with a few used ones or take my best guess with either new or used. Ideally I would want to upgrade arm, cartridge and phono at the same time, at least arm and cartridge. But if you have a Continuum with SAT tonearm and Ypsilon phono stage you better try just about anything regardless of price. A lot of work, but fun too. Poverty is not a sin but it sucks.