Ah, Eugene! We were there for 5 years when DH was in grad school on one of the worst graduate student stipends in the US, so we have intimate experience with living a mustachian lifestyle there.
-It's hard to believe that a more bikeable city exists. Equal, perhaps, but not more. There are bike lanes everywhere, and the hippie culture that infuses the city has helped ensure that drivers are aware and accommodating, and that bike parking is always easy. But have a really good lock (not just a U-lock with the circular key: DH's bike was stolen in our first week, even with the U-lock. The cops told him that bands of thieves in vans travel from Seattle to SoCal stealing bikes along the way, and Eugene is a hot spot).
-The mountain biking is particularly good.
-Housing can be pricey, but you can find that out easily enough online.
-There are plenty of options for bulk foods (thanks again, hippies!), and one natural grocery store, Sundance, has a shelf with distressed 1/2 price produce. We would often wander down there and pick up whatever was on that shelf for dinner.
-Go to any park or even the side of the road to pick gallons of wonderful, free blackberries. We even got a bunch of apples from a state park one year and turned them into pie (although we'd make applesauce today).
-There is a ton of free entertainment. Beyond the parks, you have a free summer Shakespeare in the Park series, where people eat dinner on the grass while they watch a play. Spencer's Butte, a short drive from town, is a free and popular day hike. Again, pack a lunch at eat it at the top. Hell, the people-watching downtown is a sport in itself.
We'd move back in a heartbeat. Best o' luck!