Buy what sounds good to you.
As others have said; don’t be afraid to buy lightly used gear. Your money goes a lot further. But, also be careful not to pay for the other guy's usage and his time owning the gear.
Reach a little on your initial purchases. It should slow down upgrade-itis. And, when you do upgrade, make several jumps (or quantum leaps) up the chain. Don’t get nickel and dimed to death with a never-ending cycle of small upgrades.
When you get to "Damn, this sounds good with almost everything I listen to," stop buying stuff for a while and just listen to the music.