Culturelle is $20 for a month's supply and Digestive Advantage is around $10 for a month's supply and both should be located in your nearest chain pharmacy (I have found both at an Eckerd's and Walgreen's). You may want to try them if you don't want the hassle or cost of the other stuff. Like everything that goes into your guts, there's no guarantee that they will work for you, but--who knows?--they may work better.
I agree with Bluemeanies, though: insurance won't pay a dime for OTC meds, and, as far as I know, there's not a prescription probiotic to be had. You can write to the company that produces the product and tell them that you like their product, it has helped some, etc.; a lot of companies will send customers coupons when they write in like that. If you're really having trouble affording your meds, you can also write the company and say as much. A number of the big drug companies are offering discount cards and/or coupons to people who otherwise can't afford their meds; the makers of probiotics might be smaller companies that aren't as philanthropic, but you never know until you try.