Besides the numerous taco trucks and taquerias that get most of my budget dining dollars, here are some of my favorite cheap eats in Sonoma County.
Whenever my parent's visit, they ask for one meal at Pack Jack's BBQ south of Sebastopol on the Gravenstein Hwy. (116) with a Texas-style pit. Our family favorite is the lamb ribs - a half dinner ($5) is plenty for one which includes two sides (potato salad, cole slaw, or bbq beans- all good) and a dinner roll. We get all three sauces - mild, sweet and hot (really hot!) - on the side to mix and match as we like. The sweet potato pie is good too with a crisp flaky crust - but they sell out fast and half the time we're out of luck.
Willow Wood Market in downtown Graton has great sandwiches. My favorites are the roast pork loin with melted real Italian fontina and arugula and I also love the egg salad sandwich. I think these are about $7-8, and big enough to split with someone else who's not super hungry.
Hamburger Ranch and Pasta Farm on the north end of Cloverdale makes great burgers from the classic cheese burger to Latin Lover (with jalapeños etc.). They grill outdoors on Friday and Saturday nights during the summer and somehow these taste even better. Soups are homemade and change daily. Brews from Boonville are really cold and the blues are the tunes of choice.