This is something that I am also trying to figure out how to do.
Web scrappers tend to control a web browser process. Some use phantom.js - which is a headless web browser - optimized for that sorta thing
Some websites will detect that a web scrapper is trying to access them and block it, so you need to authenticate your scrapper as a browser to them
There are multiple modules on than for python. Some other people write their web scrappers in ruby on rails.
I've done my first one in autohotkey+IE (COM) - it's pretty lame choice but works. AHK has regular expressions and even a builtin gui toolkit. It's full of goodies.
Python is another great one if you are more serious about it. You can use python+flask+beautiful soup (its better than regular expressions) to make a web app, but I have never tried to make a web app that is a web scrapper yet. Might give it a try in the future, as I am getting pretty far with my research there.
I have encountered the security iframe limitation just like you have - cross domain access forbidden, but am yet to figure out a way to get around it in an elegant way. Java script or jquery wont allow it, so you might have to do something extra to get around that.
A strategy I want to try- download the target html to your localhost folder (flask), then load it inside the iframe- that way it will be on the same domain as the page trying to load it inside an iframe