I don't think anyone can tell you exactly how much its going to cost. You can do a little research, starting on tangent's site, he actually already has a pretty good parts selection and location guide. You can get the board, the el2001's, the rail splitter, the Brown-Dog Adapters, and some of the caps there. According to your opamp selection, he won't have those. Newark has the AD843KN's, which are DIP-8, and they also have the SOIC version. The AD8610 is kind of hard to get, try analog devices direct. Its SOIC only, and single (I think). You will need a brown-dog adapter (SOIC single to Dual Dip, or DIP-8 single to Dip-8 dual), depending on which package you get. Both if you want to try both the ad843's and the ad8610's
Then, try to get as much of the other stuff from Mouser, what you can't get from mouser, get from Digikey (cases, connectors, wire, solder, resistors, some capacitors, and the regulated wall wart). Mouser seems to be a little cheaper on the things they do have, such as the Dale/Vishay resistors, but I think Digikey is going to be required for some of the stuff.
The hardest part is going to be sourcing the Alps pots, and the "premium" capacitors. PM JMT on this board for Elna Cerafines, and also check out Michael Percy for pots, and also caps and connectors and solder/wire.
You can try to make a decision on how much is good enough, i.e. Panasonic FC caps from Digikey, Nichicon Muse from Michael Percy, or the high-end, Elna Cerafines or Black Gate's, from JMT or Michael Percy.
Even saying all this, I think its going to be hard to spend over $150, unless you want Black Gate caps (some of those are $150 each!!), Alps stepped attenuator, and all Cardas top of the line connectors!
You also might consider building the first one with "generic premium" parts, such as Panasonic FC caps, and possibly a Panasonic Pot, and connectors from Mouser, Digikey, or Parts Express, then upgrade piece by piece as time/budget allows. Maybe get two boards, and double the opamps and resistors when you make your first purchase, so you wouldn't have to unsolder stuff from the "generic" version. Plus, a lot of people would like to hear an A/B comparison/opinion of a "maxed out meta42" vs. a "not maxed out meta42"
You could probably easily do it this way for under $100.
Good luck, I am going through the same thing right now, but I am not using the board, and different PS and buffers, but its going slow, because I am building the whole thing "from scratch"!
