Except for phono cartridges (which I like to change about annually), I don't think I buy all that often. I used the same Linn Sara speakers and Linn LK1/LK2 pre-amp/power amp combination for almost 20 years. The LP12 turntable I bought in 1985 was sold to help fund the purchase of a new Cirkus model LP12 in 1993, along with an Ittok LVIII tonearm, both of which I'm still using. I did buy a Well Tempered Record Player, mostly to see if a Grado cartridge would be happier there. I get no hum, and the cartridge is very well behaved on that lightweight, damped tonearm, but all things considered, I prefer the Linn.
Some of the pieces have started to fail: the LK1 was replaced about 3 years ago, and the speakers and power amp were replaced this past spring. I'm happy with solid state electronics from Audio by Van Alstine and Vandersteen's little 1C's. I'm not planning any further changes for the next 15 years or so.