You're on the path suggested in Thom Hogan's article. While it is possible to cut some corners and delay the expense, you probably need to think about how you will evolve to a long term objective.
Here's how I would lay out that path:
Step 1 Good ballhead with quick release basic legs plates
Step 2 Upgrade the tripod legs
Step 3 Add a lever release Add custom plates / L-bracket
I find that a good ballhead is one of the biggest steps you can take in improving image quality. The ballhead is the one item that can't be replaced with an inexpensive knockoff. You lose too much in terms of smooth operation, clamping power, and overall design. And a well designed top of the line ballhead is a joy to use - and you won't ever look back. Buy it once and buy a quality product. Whatever you do, stay away from proprietary plate systems - go with the Arca Swiss standard.
For the legs, you can save money with a good product from someone other than Gitzo. The Feisol, Benro, and Manfrotto models are just fine for a first step. You can save a lot of money with alloy legs instead of carbon fiber. Something like the Manfrotto 055 is a good option. Good tripod legs have a pretty good resale value so you might find them used, or be able to sell yours when you upgrade later. Stay away from integrated legs and heads - the quality is low and it restricts your ability to upgrade.
For plates you can probably get by with a generic Arca Swiss plate for a start. They are cheap and good utility items. Longer term you will want a replacement foot for any lens, and custom plates for the camera body to prevent loosening. And longer term you will probably want an L-bracket for your camera body.
If you have plates from different sources, you may be better off with a screw type quick release. I strongly prefer the lever type quick release, but it costs a little more and may need to be repaired or replaced over time. If you go the lever route, tolerances are more important, so you either want a clamp that can be adjusted - like the Markins lever release, or buy from vendors that are compatible - like RRS and Wimberley.
Replacing a clamp is not a big deal unless your clamp is attached with red Loctite or a similar product that is hard to remove. You can avoid that problem by purchasing a head and clamp that are not attached and combining them yourself.
I think you'll need a minimum of $600 for a starting kit. That's $350 for a ballhead, $200 for legs, and $50 for a generic plate. Lacking the budget, you'll need to try a different type of head - maybe a geared head or a pan tilt head - and plan on an upgrade at a later date.