Reddit mentions of Sound Devices MixPre-3 Portable Multichannel Audio Recorder/Mixer, and USB Audio Interface

I would get the K & M Microphone Stand with Telescopic Boom Arm. IT may be easier to get a desk based stand but this will remove the microphone from physical contact with the same table you are using for your computer/recorder/mouse to prevent noises from translating from the table through the stand to the microphone and into your recording.

I would urge you to go higher than $100 for the microphone to a large diameter broadcast dynamic microphone like the re20 or the re320. You can get a package from BSWusa.com to include the shockmount and the pop filter that's the best deal around but if you want to stay under $100 per item I would recommend either the Samson Q2U or the sE Electronics V7.

If you use the sE Electronics V7 I would recommend one of the Makie Audio Interfaces. The Mackie Onyx Artist is currently under $100 but if you wanted to futureproof yourself with the ability to expand to one additional microphone I would highly recommend going with the Mackie Onyx Producer instead. The Samson Q2U can output via USB and XLR at the same time so you could go into the Mac and a XLR connection (like a portable audio recorder) at the same time with no need for the Mackie Interface.

The next one is outside of your price range but I would highly recommend that you invest in a portable audio recorder. Yes you can record straight to your Mac but I've seen so many software recorders fail and lose episodes that a hardware recorder is generally best in my opinion. For your application I would either recommend the Zoom H5 at $270 or the Sound Devices Mix Pre-3 at $650. Either will work for you but the preamps and options on the Mix Pre-3 are pretty sweet. Also, if you upgrade to the re20 or the re320 the preamps on the Mix Pre 3 won't be working as hard and might end up giving you a cleaner sound. The Mix Pre-3 can also act as an audio interface to your Mac as you record at the same time so there would be no need for the Mackie Audio Interface. You can use the Zoom H5 without an audio interface as well but you cannot record on the Zoom H5 and pass the audio to your Mac via USB at the same time.

There's other things I would consider as well but if it was me I'd grab the Zoom H5, the sE Electronics V7 and record straight to a the Zoom.