I responded to someone in another thread regarding the Tell Bell potty training method and got quite a few private messages. I'm sorry about the duplicate post, but it seems a lot of people are interested.
Tell Bell - Kelston Products
Take a look at the website. I know it seems ridiculous at first but Cooper is trained 100%. The Tell Bell comes with instructional video and manual. I bought the Tell Bell when Cooper was about 10 weeks old. It took about 4-5 weeks before he rang the bell and the first time he did I was such a proud mommy!
When I took him out to potty I put his leash on, took his paw and tapped it gently on the bell and went outside. I continuously said "go potty" "coopy go potty" every time until he finally went. I always brought treats outside and made a huge ordeal when he went. If he didn't potty, no big deal. We just tried again after a short while.
I work from home so I had the time to properly train Cooper. I would take him outside about every 30 minutes or so. My vet always told me to take him about 5-10 minutes after he ate and also right after he chews on toys.
I'm sure you can purchase a regular office bell at Walmart or an office supply store much cheaper. However, I wanted all the help I could get so I bought this product.