I built up all the pedals on my pedal board - 12 in total - with a buddy. There are a few sites that provide circuit art, component layouts and assembly instructions that you can download for free. Then there is the component costs - cases, switches and jacks being the most expensive.
I think it makes most sense to tag team with a buddy and build up 2 of each circuit, as we did. Components like resisters tend to come in bags with lots more than you'll need for a single project, so to get descent economies - my pedals cost around $50 per - you should plan to build up a few. Building 2 of each gives you a better chance of getting at least one to work that you can use to trouble-shoot the other. As far as tools go, a good soldering iron, pliers, a magnifier and a good drill-press are the most important.
You need really good eyes, a strong magnifier, lots of time and patience. Aside from cost savings, there is a tremendous amount of pride from plugging in a bunch of wires and componenets you've slaved over and have it work first time. DIY is the best way to get a unique sound - my rig's got tone to spare. Besides - it can be a lot of fun if you don't take it too seriously.
As an aside - the most complicated circuit was a delay and both worked first time. OTOH it took me 4 tries to finally get a chorus circuit to work - it's amazing the amount of trouble I went to to put so much cheese into my rig. If you want to see a pic, follow the link in my sig and go into the Music section - the pic's about 3/4 of the way down the page. Good luck!
