I would say that the 2 most important parts of audio are both ends, where mechanics meet electronics, source (cd player, TT what have you) and of course speakers. Yes the preamp is vital but mainly an impedance check would do, if you can use a passive preamp better...
Now about the caps, I have tried a bunch of caps but I havent gone for the Duelund, I do think they are terribly expensive and it does sound funny to spend more on caps than on drivers, but when you have a 3k cable....
Some of my favorite caps are Jantzen Silver, Mundorf silver oil and Vcap oimp (the values that I use does not allow for teflon)... You would do fine with any of them really and maybe save a little, or live dangerously and get the Duelund, I am sure they will be wonderfull.
Mainly with caps these quality you end up with the flavor you like best...