If a company starts automatically charging you for something that you were only testing to see if you actually wanted to purchase it in the first place, would the charge thus make you determine this would not be a company you would want to get into a contractual relationship with? For me personally it would say a lot of that particular company's business practices and would scare me away. I'll leave the ADA questions to the experts.
KA20003, you may find this link useful. 18F, via cloud.gov, just rolled out a free sandbox for Federal Agency's use.