How about a zoom handheld recorder? Even the cheapest one has stereo line in and doubles as a USB sound card and you can go into your iPad or iPhone with the relevant adapter.
http://www.zoom.co.jp/products/h1
If your budget can stretch up a bit, the more expensive models give you more inputs, swappable modules for mics, 1/4 inch inputs, etc.
http://www.gak.co.uk/en/zoom-h5-handy-recorder/99515?gclid=CJffuse5pcMCFcvJtAodCQYA9A
Works great, straight into most iOS video apps.
There are of course many other brand equivalents that will do the same job.
The beauty of this approach is that you get more than just a sound card plus extreme portability for little outlay compared to buying a cheap audio interface.