Ah ... brings back memories of when I started in ... "84 HP is going to be plenty!" Such innocent times. The best financial advice you can give someone getting into euro is probably "don't do it!"
Glad the rack is working out though. It does become an obsession, and I often wish I could go back to when I started to emphasize a few things, most of which has already been said and some of which it sounds like you're beyond at this point, but just to add my version of agreement(s):
- Don't waste money on a fancy case, unless you need to be mobile and are going to gig or something. All you need are rails, something to mount them on, and a way to have busboards behind the units. I paid like $400 for a "custom" 2x 84HP case with a shitty PSU. Waste of money.
- Don't skimp on space itself, though -- if you think you need 104 HP, get 3 rows of 104 HP. A Synthrotek Cheeks of Steel isn't a bad place to start. You'll thank yourself later.
- Don't skimp on power. Get an m/15 from Trogotronic with 3 busboards right out the gate. It's actually a very competitively priced PSU and it'll take you a while to catch up with all the power it offers.
- Get a Mordax DATA. I almost didn't, but so glad I did - it is such a useful tool in terms of really getting your head around what the modules are doing, if you're a visual learner -- especially EGs and the like. Absolutely worth it just for the oscilloscopes, spectrum analyzers, and voltage monitors, but it has VCOs and clocks and stuff too. Can't go wrong.
Beyond that, the usual stuff that's easy to forget or not see the value of: offsets and attenuators, inverters and polarizers, mixers (both DC and AC), VCAs, and lots of mults.