Reflectors to use with flash/natural light

So i thought this would be the best place to post this, but i was looking to get a reflector while i am doing photo shoots to use to reflect (obviously) and to bounce flash off of, and have a few questions:

What is a good size? I know that a big one will reflect more light, but there is obviously a tradeoff between size and practicality.

What is a good brand? I know there are several out there, and while reading Joe McNally's books he loves the Lastolite Tri grips, what are your thoughts?

Do you have any links to ones that you recommend?

I am not looking to go cheap, and want ones with several different layers (gold, white, black, etc.) but is there a reason to go the more expensive route?

I would really appreciate your help, I think this is something that is important for flash and natural light photography.

Thank you.
-Bryan

A large (4' x 5') piece of white foamboard would work very well and is a lot cheaper than a "photography" reflector.

Thank you Austin.Manny.
I know the more expensive ones are more portable. Does any one else have any recommendations?

If your after an economical different surface option reflector than the tri-flip (tri grip with covers) is your best option really.

I have a trigrip but I rarely use it - I use my california sunbounce mini 3x4' far more often and prefer it. Its not much more unmanageable and I can set it up to be self standing etc.