As a fairly newbie to DIY, and on the steep part of the learning curve myself (theory part) I have to say that the advise here is good. Constructing a kit is one thing, going full blown DIY is quite another. I think you need to judge for yourself where you want to come in.
Gaining the requisite soldering skills and basic technical information is something I think all audiophiles should gain. This may be a bit contraversial but I think it opens up a lot of great value oriented gear, ability to fix minor problems with gear and do minor parts mods under the advisement of well experienced peers. Overall I think this sort of skills will come in handy if you like to experiment, tweak or change gear at all. The committment is minor as are the costs of simple tools needed for such DIY'ing.
The next step is a major one IMO. To go much further than the above requires a lot more understanding, patience, commitment, TIME and a lot more spent on tools. This is where the value in DIY can deteriorate. The learning curve is steep. I recommend this road only to those that take it as part of the hobby itself. For me this is fun, a brain excercise and opens a lot of possibilities.
That said, I think the next step can be quite illuminating a rewarding. First, it helps you gain the tools to dispel many of the myths in hi-end audio, so you can start to spend money where it will gain you more in return. But more importantly, to me anyway, it allows you to take a number of steps up the food chain in small increments.
Take the UcD building thread for example. In order to make an amp upgrade, a DIY'er can make some changes, maybe even dramatic ones without having to sell an expensive component at a major loss and buy an even more expensive one to get gains. One can just experiment with different design, parts, etc, which usually come in smaller increments (although do add up, don't underestimate that) which can be easier to digest than kilobuck component swapping. Quite often, accumulated parts can be recycled if one changes to much different path also, commercial product buying can't make any such claims.
my $.02