The attraction of the Klon stems from it not being a tubescreamer, so no mid hump, if that's your dislike with less coloration of your guitar signal, which is why they call it an transparent overdrive. It also does sound great as a clean boost pushing your amp, as that was part of Finnegan's design. It's probably what most people use it for. Because of that it has a 18volt chargepump that converts 9 volts input into 18 volts for more headroom. It is however not a true bypass pedal but it has one the sweetest signal buffers ever built that will bring shine to your guitar signal. Only Pete Cornish's buffer comes close to the Klon's buffer mythical status. Seriously, there are people who build just the Klon buffer to spice up their guitar signal.
Pricewise it doesn't help that it has become of a darling of the people on the Gear Page, who can be like blind Lemmings when it comes to (boutique) gear. And they're probably the ones who are driving up the price for a real gold one up to a thousand. Because as everyone knows, with every revision and redesign a pedal gets worse.
There's also the mystery of its creater, Bill Finnegan, who claims the circuit only sounds best with his mystery germanium clipping diodes, of which he bought every one of them ever made so boo yah to the cloners. Even though technically if you only use a Klon(e) as a clean boost to push your amp into overdrive the clipping diodes don't even come into play. His mystery diodes are the only unobtainium parts as the rest of the circuit is what you can get at every other electronics store. No out of production NOS IC's, no carbon comp resistors for extra mojo. Just find the right substitutes for the germanium diodes and you can start. The Russian D9E germanium diode is now considered to be the best substitute, but who knows, anything can work if it sounds best to your ear. Switching between different sets of diodes has become a very popular mod on Klon(e)s.
If you want a transparant good sounding overdrive, as in no mids hump with less coloring of your original signal the Klon Centaur and Paul Cochrane's Timmy are probably good choices and both original designs. Both have been traced by the DIY community and commercially cloned. Interestingly although there are a lot of DIY'ers offering Centaur boards on the forums and their own websites, the Timmy not so much, as everybody seems to respect Paul Cochrane for being a nice upstanding guy. The same cannot be said for commercial builders as Danelectro and Vemuram have shamelessly copied the Timmy. And EHX of course copied the Centaur as the Soul Food.
Aion Electronics has an interesting essay on the Klon
here.
If anyone doesn't want to pay $600 to a $1000 for a real Klon and is not afraid of some soldering you can get Klon(e) Centaur pcb's here:
Aion Electronics
Pedalparts.co.uk has both a
pcb as a full
kit
Madbean pedals, has also a kickass forum with very helpful members. He does give weird names to his pcb's though. The Klon is called the Sunking II. He also has the Kingslayer, which is a modded Klon.
GrindcustomsFX offered the Chimeara until recently, but its been discontinued. I got one of the last boards for my build and it sounds awesome! They're working on a new version called the Tusk though.
Buildyourownclone had a kit based on the Silver Centaur version, called the Silver Pony. It has recently been discontinued, but you come across a kit here and there. BYOC kits are well thought out with inexperienced builders in mind, with the best build documents, and also a very helpful forum community.
I've ordered boards and kits from all of them and I can vouch for all of them.