Search for the best bio-mug

We are digging deep in cyber space for the most enviro friendly travel mug to offer at our shop. So far the choices are narrowed down to; a hideous 60-70% recycled tumbler (at a very low price), a "biodegradable polypropylene" tumbler (said to biodegrade in a managed landfill in 1-5 years), a corn "plastic" travel mug (not dishwasher safe and pricey), and then the stainless steel travel mugs all look the same (boring) and would probably never be recycled at the end of its life. I would like to make the best purchase possible... something unique, practical and earth friendly (without breaking the bank). Any suggestions out there...?