Oh HAPKAT . . .
. . . You do have a predicament.
I'm afraid I cannot help you too much because things are so very different here in Canada. As a matter of fact, insulin is one of our cheaper meds for controlling diabetes.
I would suggest you talk with your doctor and your pharmacist about any agencies that can offer assistance in covering the cost of meds. As MONET mentioned, also contact the American Diabetes Association. You might also want to get in touch with the manufacturer of the insulin because sometimes they offer assistance in obtaining medication as well.
Unfortunately I have to agree with a couple of AMBER'S comments -- it is very unusual for someone who has progressed to insulin (for whatever reason) to go back to oral meds alone and even if you did go back to orals, you would likely need much higher dosages than you were taking before and consequently you would not see much of a cost break anyway.
At risk of sounding like a broken record and being accused of preaching to the converted . . . the very best thing you can do for yourself is to get the weight down. Losing as little as 10% of your current weight will help your body become more sensitive to the action of whatever meds you are on. I know it is true because it has happened for me. I take glyburide, metformin, and actos in addition to two injections of insulin daily. Since I've lost 45 pounds, I've been able to cut those medication dosages by approximately 1/3 (with the blessing of my doctor, of course).
Good luck, my dear . . . keep us posted on how things are going . . . and remember we are here for you and we have very broad shoulders and attentive ears.