I would like to mention that there's a new MyGolfSpy forum that I think many members would enjoy and they are having a big contest giveaway for joining and participating in their forum. For more info, check it out HERE.
MyGolfSpy is great if you are an equipment buff.
Over on that forum, there was a thread about what core tools should a clubmaker have to get started.
I think this can also help the very serious golfer as well.
For starters, I would suggest getting a vice. You need one for grips and shaft pulling and other procedures and you can get one for about $20.
From there I would look into a lie and loft bending machine gauge.
It's important to note, especially with forged clubs, that after awhile of hitting off of hard ground and mats that lofts and lies can change. Clubfitters need to toy around with these all of the time, the serious golfer can constantly check up on their equipment specs. You can get one for about $300.
Next, a swingweight scale is important as well. Particularly if there's a change in shafts, grips, etc. While one can estimate the swingweight difference, it's better to be exact. Also, get the swingweight scale that measures static weight of the club as well.
While swingweight is important, you'll find static weight plays a factor as well. I have D5-D6 swingweights in my Hogan IPT irons. But with my Apex PC's I have D6-D7 swingweights. Why? Because the static weight of the PC's is less and I can't get the right feeling so I put some more lead tape on them
You'll also need either a blow torch or a heat gun if you're going to be doing re-shafting. The blow torch is cheaper ($10 or so), but the heat gun is better for those less confident in using a blow torch, but is more expensive ($50).
Lastly, and this is more for the serious golfer, but I would also consider a shaft frequency analyzer.
This measures the flex of a shaft. Believe me, I've had it as bad as an X-stiff shaft actually measuring a Ladies Stiff before. A clubmaker may have little use for this because shafts have no guarantee when it comes to their flex and a clubmaker can't afford to junk a shaft because it's out of whack. However, if you're a super serious golfer and can afford it, I think the frequency analyzer would allow you to junk those shafts that are way off. You can get one for $300 - $500.
Either way, I think all golfers who want to get better should know the ins and outs of their equipment and toy around with them to see what feels best and what they don't like. A forgotten art in today's world of custom fitting.