I'm sure that there's a few people who are hesitant to buy one of these kits because they've never done soldering work on a PCB before. And while these kits are very affordable, it's a lot of money to lose for something that you fear will end up not working.
I haven't built one of these pres yet, but I can tell you that it's not very difficult, if you have a little experience at this. I got my experience building stomp boxes. There's a few DIY stomp box kits out there that are crazy cheap, and I hope this wouldn't be considered spam, but BYOC even has a very simple practice kit to help newbies get started. Their instructions are very detailed like Tim's, along with a helpful forum.
I've discovered from building about a dozen stomp boxes that distortion/fuzz/compression unit are extremely easy to build while modulation is bit more complex. 50 bucks for a stomp box kit is a hard thing to pass up if you're looking to learn how to build DIY electronics from kits.
After building a dozen or so stomp boxes, I can look at the instructions on Tim's pres and know that they not difficult to build. But I am glad I have some experience at this.
Just a thought I'd figure I'd pass along. Happy building everyone!