Develop an automated program to check competition - repost

We have a website that needs to be on top of being the best price. I need a program that will go to our competitors websites and check all of their products prices and put the product name and price into an excel sheet for thousands of products. The competitors websites are not password protected in anyway, the program will simply need to connect to their website, fill out a few drop downs, be redirected to another page based on selection, click next and be given a price, grab that price and put it into a specific csv excel format. There will be a total of 8 sites but they mostly all function in the same manner. Ideally the automation would comb one site at a time but would do all 8 sites without out needing any human interaction. It would them bring all results to one csv file. We understand that if the competitors change their website the program would need to be altered to continue to work, please describe your long term plan to make sure we have working software if this happens to prove you have read this requirement. Site examples will be given upon request.