Easiest/Cheapest way that I know of...
Find a bar/restaurant in your area that serves them
Talk to people that work at said bar restaurant and casually mention that you are a homebrewer (this works best with kitchen staff or managment)
Mention how great you think these cool little bottles are
Many times they will give them to you...
If not, find out who the distributor is and call them. They are usually picked up from said bar/restaurant already sorted, and no big deal for them to set you up with a case or two for deposit (although a few homebrews always sweeten the deal)
PS none are cooler than the Gulden Draak bottle. Enameled white on the outside with a label you can take off with no effort at all. I sneak them out of bars all the time. Same with the big German wheat bottles.
