My strategy is simply. Buy what I want. If I don't have the money, save or readjust expenses until I can afford it. Or tell my wife that near duplications are there in case both of us need to shoot at the same time.
Until 6 months ago I was drivng a 12 year old car - photography gear often wins out.
I still drive a Mint '91 Lariat F-150, Why buy a new car? That's like 200 F/2 monies.