A lot of interesting issues here.

Bike shop choices: SoCal is riddled with bike shops, unless you're closer to AZ than the ocean. Go to the nearest Performance Bike ( I reckon City Centre PKWY and Ronald Packard FWY) and get one of their $300 fuji Nevada 2011 models. Take good care of it and you can sell for at least $150, making your depreciation less than auto, probably even less than moto insurance for the next 6 months. It'll ride much better than a Walmart rig.

CL: If you're mechanically inclined hit craigslist for a $100, say a 1994-ish MTB with a rigid fork that's in good shape. You'll be able to resell at same price if you get the right one and keep it in good shape. STX components or better.

There are fancy pants bike shops here too, but there are plenty with rides starting @ $200 that blow Walmart rigs out of the water.

I'd rather buy and resell a bicycle after 6 months than car or moto.