OK, I don't even have the system and won't until, oh, next year, but I'm looking at budgets:
http://www.kerrison.karoo.net/water.jpg
I even know how I'm going to route everything, lol.
Edit: Obviously what I buy in the end will be based on what the blocks are for and what's available, but my budget is £300 for w/c, and so I thought I'd price up based on what's out there now...