I haven't shown anyone my printed portfolio in ages.. It kind of sucks, since I spent $600 dollars on it LOL.
I'd recommend spending a decent amount - agents, buyers and a lot of prospective clients can tell a costco print from one done properly, and expensive prints in a cheap case don't help at all either. I use this case myself: lost luggage and used an epson 2880 to make my prints.
lost luggage is nice, and not overly expensive but, you might find something else here at the photo'directory.com