since it sounds like you already have the project car, and others have already told you how they pay for their projects, let me add this tidbit.
MAKE A PLAN FOR THE CAR AND STICK TO IT! You'll never get it done, and you'll spend twice as much money as intended if you just go thru each little step on the car as it comes up and you say "well, I could do this now while I'm in here." It'll drive you broke in no-time and you'll spend you entire budget to only see the car sitting there.
You can physically write it down or sit in front of your computer and type it out, doesn't matter, but it needs to be done. Sit down and first develop an idea for the car as a whole. Once you think you have an idea of how you'd like that to go, then you can look at specific components and develop how you think you'll actually make the car become what you want it to (drivetrain, interior, suspension, brakes). THEN...and this is the important step...put together a realistic idea on what it will cost to do what you just laid out. You can't lie to yourself and say you're going to buy a LS1 running longblock with ECU and T-56 for $1000. Once your budget is done if it's too much (say your idea for the whole car was to be done for $12K and you just spent $9K of your budget on the motor) you may need to go back and rethink some steps/parts/priorities.
Once you have that plan laid out, manage to it. You might have to skip on upgrading to roller rockers so that you can get the disk conversion for the rear etc. Without a plan like this that's how many projects end up never being finished, they're in project car purgatory. The other upside to working toward the plan is that it'll help you with the issue of wanting to be done right now. You'll be able to check off parts of the plan and track your progress.