If you decide to use a digital voice recorder, we use this Sony Digital Voice Recorder ICD-PX Series, with Built-in Mic and USB, 4GB Memory version.  It works on both Macs and PCs, has a lapel mic, and built in 4 GB of memory.  We have found this is more than enough memory.  It usually goes for around $50.  There are also numerous free voice recorder apps that work on your phone.  Just remember to silence all of your notifications before you start.