Actually, the scraping is done in the client nowadays, so no server costs at all. The client is basically making a visit to the page, and then the relevant info

Actually, the scraping is done in the client nowadays, so no server costs at all. The client is basically making a visit to the page, and then the relevant information is extracted and presented with a different UI than the original site. In regards to your second question, I'd say it is not too much effort. If you're a skilled web developer you can spend one day getting familiar with the iOS web platform and then build a cool app. There are tonnes of material on Google and since you can test the web app using iOS Safari there is no reason to spend money on an iOS developer license until you're confident that the app idea will work.