I would suggest two low-cost and one "mid-cost" solutions for interview recording (I skip the high-cost variant which would require an external microphone).
Low-cost: a) If you own an Apple iPhone, the App "iSaidWhat?!" not only records with a good quality but also has a very effective audio cutting tool. In my opinion better than the "Hindenburg Field Recorder" or the "FiRe 2 Field Recorder".
b) If you own a Samsung, HTC, Sony, ... smartphone with Google Android then I would recommend the App "Field Recorder" which has an interview preset that turnes the screen upside down so that the internal microphone points to your interlocutor.
Mid-cost: While the low-cost variants are far below 10$, this variant is 200$ but still fair enough I would say: The Field Recorder "Zoom H2". It has switchable microphone directional characteristics and surround recording, very useful if you have loud background noise to focus to the interlocutors voice.
BTW: All three options produce material which is broadcast-ready after post-processing.