What do you consider inexpensive?
Banjo Brothers makes a couple messenger bags $65 and $80 . They also have a range of commuter backpacks.
I'll vouch for their quality and warranty. It has a tough build and contents stay dry during a pouring rain. About three years bac, I had my U-lock in my left side large commuter backpack pocket when the lock snagged a passenger side rear view mirror as I passed a pickup truck. It tore the pocket at the seams and opened a 1 in gap in the main compartment. I sent the pack to Banjo Brothers expecting to pay for the repair. Banjo Brothers opted to exchange it for free.
I own a large commuter backpack and a large messenger backpack and have owned a medium and large Timbuk2. Bag build quality is on par, and while Timbuk2 does have better style, the price difference is significantly higher.