I always bought the new shinies (well, most of them). Daemons came out, I bought skullcannons, I bought Fateweaver, a new burning chariot...
Tomb kings came out I bought snake-knights, stalkers, sphinxes...
The only time I didn't buy cool new stuff was when GW was too stupid to actually sell it (like the Hierotitan, which I then scratch-built since there was no model to buy).
This, incidentally, is the huge flaw in the "old players never buy stuff" theory - if you make the new stuff worthwhile (without pissing off your player-base buy just making the new shinies overpowered), your existing player-base happily buy new toys. This is a business model that PP have mastered - every army gets a small influx of new shinies every year. The metagame shifts, but isn't completely wrecked, and existing players that enjoy the game support the hobby and the company by buying, and their enthusiasm drives the game forward with the player-base eagerly promoting the game to new players. Often for variety those old players even branch out into entirely new factions / armies, again driving new waves of purchases.
It's not a novel approach, it's not groundbreaking - they retain customers through good service and by delivering consistently high quality across the product line (by this I mean service to customers, actual model quality and maintaining a good environment to play with those models). Some might even think this was the front page in "baby's first business", and yet it seems to be a recipe that still eludes GW.