The first time I experienced a personalized bib number was at NAOC 2010. And I was so enamored by it that one of the "must haves" when I directed the 2012 IS/IC Champs were personalized bibs.
For the participant, having a personalized bib is cool in that that it can convey useful information to you (start times) and useful information to the event staff (knowing your name). A personalized bib makes for a much better event souvenir. I have several maps with bib numbers displayed at my desk at work, and the ones (by far) that get the most comments are the ones with professionally done, personalized bibs.
And just as important, I think personalized bibs encourage more social behavior, since you can put names with faces and race results. One of my primary goals at 2012 IS/IC was to create a social atmosphere with all of the juniors, and having personalized bibs certainly helped that.
I went through
bibnumbers.com (which is coincidentally out of Ottawa, Gord). They were one of the better vendors I worked with. We had custom graphics and personalized names (but no color, which was another option), and they were $0.42 USD per bib. I'm not sure of the material, but it was same as what NAOC 2010 had.
That said, after seeing what they had at 2013 IS/IC (which were done by Ed), I think I'd go that route next time I need bibs. He can customize a lot of orienteering-specific info, print in color on Tyvek, have a quick turnaround, and he can do the graphic design, too (for those who aren't so graphically inclined).