Get a decent inkjet printer and use a simple stitched binding. Make sure to not get an Epson printer if you need to do a lot of these as the paper feeds on Epson printers are finicky and not suitable for a lot of pages.

what i did was print them on top quality paper and I left them as single sheets(A3), I then found a nice black leather case to put them in.

I use a color laser printer. I used to bind them together with a 2-hole punch and those medical folder clips. I don't bother with the binding anymore as they usually get taken apart and passed around during the interview anyways.

This is probably out of your price range (since you said "cost effective") but I'm starting to see folks put their portfolios on iPads.

For printed pieces (a brochure or poster, for example) I'd rather have the actual printed piece to examine, but for showing electronic media (web pages, Powerpoints, PDFs, etc) an iPad works pretty well.

I did a horizontal 8.5x14 metal screwpost binder. It was about $60-70 I want to say but you can find similar stuff online if you're looking for cheaper versions. It's great if you need to switch/add stuff. Plus, it looks and feels cool.

Always a plus to take in actual printed samples if you have them for the interviewer to take a look at, especially if it's something more involved than say, a poster.

Best of luck!

If I were you, I would invest in really good printing on high quality paper stock. A print from a machine like the Indigo machine can have you go gaga over the richness of colour.

I use an small SRA4 sized art cardboard binder that was a hand me down from a senior of mine and it is awesome.

If you find the right deal for a print on demand publisher, you can probably get a well printed and bound, one-off, glossy book for less than ink jet cartridges will cost. My wife has found deals that are almost free except for shipping. I can't remember what or where those were, but we just used them for books of vacations photos.