I know how you feel. My 6 mo old girl is a pretty good eater, but selective about when and how often/much she eats. Some days she won't eat solids at all, other days she will eat three times a day. Usually I can count on one good feeding mid-morning. Just keep offering her food and don't fret if she doesn't take it. I mix her food up in a small tuperware container so that I can put it in the fridge for next time if she doesn't eat it now.
She was never too fond of the rice cereal (it has zero flavor), but does like the oatmeal. For fruits and veggies, I make my own (baby food is so expensive!). It's really very easy. Steam your veggies and then puree them with a blender, hand-held stick blender or food processor. The fruit you just puree and buy plain old applesauce (no sugar added). Freeze the pureed food in ice-cube trays (except applesauce, that can stay in the jar), and then put them in zip-lock baggies or tupperware containers in the freezer. They'll keep for a real long time.
Veggies are not her favorite, but we keep trying. There are days when she eats them and days she doesn't. Sweet potatoes are her favorite, but she's eaten carrots and green beans as well. She loves fruit! So far she's had bananas, applesauce and peaches. She likes the consistancy a little thicker, so I mix in the rice cereal (she won't eat the cereal plain anyway and it helps me use it up).
Don't worry, she will eat if she's hungry and the breast milk/formula has all the nutrients she needs now anyway. Solid foods are for fun right now. If you are concerned about nutrition, you can always add vitamins to her milk/formula once a day (she probably won't take the vitamins on their own, kind of yucky tasting).
Good luck, keep trying and just be patient.