There's a lot of responses already, so I'm sure my opinion here will die, ignored, in the ether... I don't think there's a percentage of a budget that you can copy/paste into making a system. What I can say is what _I'd_ do with $5k.
As little as $500 for used Vandersteen 2Cs or as much as $1,500 for used MartinLogans (SL3 or Aerius i are in that range).
Somewhere under $1,000 for a used amp.
Somewhere under $500 for used source components.
Throw in some interconnects.
Buy a used dirt bike. Probably a KDX-220.
The main idea is that I don't think you can build a permanent system in one fell swoop. You need speakers that speak to you personally. You're going to be staring at these things for years (probably) and that alone can fill your mind with doubts that'll affect your opinion of their sound. (Not that it's right, but it happens.)
Listen around, read, take your time and find the right speakers. Then you can find the right amp for them (I'm sure most of us can tell you the joys of the right speakers and the wrong amp... IT SUCKS!). However you do it, I'm sure you won't be anywhere near the $5k proposed... either 2/3s of it or 3 times it. =]