Upgraded X-over for Buchardt S400?

I heard the upgraded versions these speakers, with I think Dueland wiring and much better caps, and was blown away with them.  I bought the stock S400 speaker and am really enjoying them, but wonder if there is an affordable upgrade for them.  I contacted Mads and he said the upgrades network would cost $1K, which is out of my budget.  Does anyone have experience with X-over upgrades for the speaker?   Thanks.