There are many hundreds of audio-recording devices - mostly digital quality. Suitability varies according to several factors i.e. cost, availability, accessories i.e. multiple ports for additional microphones etc. It also depends on venue i.e. are you recording via an online video-conference forum, or will it be by phone, or face-to-face in a physical environment? Different tools do different things depending on venue.
Other factors can be - can you borrow tested equipment from your institution? If so, do you have IT support? A few good tips also are: 1. test the equipment prior to actual interviews as a 'dummy run' and work out best conditions and accoustics. 2. Have a back-up device in case one fails. A good quality mobile phone will often suffice.
I think Dean Whitehead aks some very relevant questions. In particular, if you are using videoconferencing software, I would recommend a program (such as Zoom), which allows you to record the interview.
The guidance/suggested tools as per the following publications may further help:
Cater, J. K. (2011) Skype: a cost-effective method for qualitative research, Rehabilitation Counselors and Educators Journal, 4, 2, pp. 3-6.
Deakin, H. and Wakefield, K. (2014) Skype interviewing: Reflections of two PhD researchers, Qualitative research, 14, 5, pp. 603-616.
Lo Iacono, V., Symonds, P. and Brown, D. H. K. (2016) Skype as a tool for qualitative research interviews, Sociological Research Online, 21, 1, pp. 1-15.
Poynter, R. (2010) The Handbook of Online and Social Media Research: Tools and Techniques for Market Researchers. United Kingdom: John Wiley & Sons Ltd
Salmons, J. (2012) Designing and Conducting Research With Online Interviews, in Salmons, J. (ed.) Cases in Online Interview Research. Los Angeles: SAGE Publications, Inc., pp. 1-30.
In Zoom you can record either the audio or audio and video, there is also an in-built screen share feature, if it's relevant. I find that having each side use headphones with a mic is good enough, even just normal laptop mic provides good enough quality