isis: that's some serious runs!
i thought i'll start with 1x Box of 300M and see how i go...i'm going to go for Dynamix UTP Solid for about ~$200
In a standard single story house, every individual run will have somewhere around 4-5m just in the walls. 2 stories may be significantly more or slightly less.
Don't skimp on cable length at the outlets or the panel. You want spare length to be able to work, and incase you need to re-terminate.
Don't run cables around loads of corners if you can avoid it. Try to make it so you can use it to pull another cable through in the future if you need something better or a cable fails. Running cables horizontally through walls is asking for trouble too. One day you'll decide you want to put a doorway in and...
Don't forget to number every cable on both ends as you run it, and make sure it still has a number on both ends of the cable after you terminate it.
When you terminate the panel try to do it in a sensible order
Honestly, 3-5k is probably a pretty reasonable quote. 30 rins is a lot, and cat6 is a pig to work with.