Meaning, if you know of a good amp, do you go and buy it first and then the speakers, or speakers first, and then find the amp to match them?
Speaking of Amps: What are the best brands to look for? Any particular "wow" models that offer a lot of value for the money?
I know Onkyo is a favorite here. Any specific models? Other brands?
Here is my rule of thumb:
Anything with a processor, you buy last. That is, surround processor, receiver, blu-ray player etc. get bought last because those get updated very frequently (e.g. Hdmi x, connectivity, feature set, 3d, sound processing, etc.).
Speakers are generally first because they are only updated, perhaps, every 3-4 years; and the updates are generally small (tweak to driver, crossover, cabinet).
Amplifiers (if you are buying external amps) can also be purchased early (provided good deals). Amplifiers have almost no features except to provide power. Updates are generally on cosmetics and connectors. If you have an idea of type of speaker you want for the future, then amplifier is easy. If you are still unsure of type of speaker (horn vs. electrostat vs. box), then you should figure out the speaker first as the speaker requirements need to factor in to the amplifier choice - Although for a, for example, entry-level type of budget, this probably isn't too big of a deal.
Regardless, you don't necessarily want to have speakers only as they need power. You don't want your money tied up in something you cannot enjoy immediately for a long time. The only time I would do this is if I scored a fantastic deal that I know I wouldn't be able to get. For example, mint condition up-to-date speakers for 50% cost. Even if you don't use them for a year or two, you would not be able to get that kinda deal after that time had passed.
Speakers hold their value over time far better than electronics. Thus, if you had to sell your system prior to it becoming complete due to unforeseen issues, if you had speakers only, you would not lose much money. If you had electronics only, you could stand to lose quite a bit of value even if they were new-in-box.