Yeah, the Linkwitz stuff seems relatively affordable to me, yet based on actual science instead of audiophile voodoo. Building one of those is definitely on my list (to replace the early 90s monkey coffins I inherited). 3000€ for a hobby is a bit much at once, but considering it can bring joy for decades that's actually quite cheap.

Though IIRC his original design used active XO with op amps (after all he's the L in LR filter) instead of going the DSP route with IIR/FIR (which IIUC wasn't a good option back when he was alive). Did his successors modernize that aspect of the design?