Print Brokering

Hi all:
I'm new to this forum but am really glad I found it. I run a new dataprocessing business outside of D.C. where I offer word processing, desktop publishing and printing.

I say all of this because I just signed up with a print broker called "ResellPrinting.com." Has anyone had any dealings with them? If so, what's their reputation? Can anyone recommend any other printers who allow print brokering?

Finally, this is a desktop publishing question? I want to create a portfolio to show to new clients. How many samples of each item, for example brochures, business cards, letterhead, etc. should I have in my portfolio?

Thanks in advance for your assistance!
dcdesigngirl