prolly wouldnt have to buy any plugins...whatever DAW you use should have its own synthesizer which you could create a sound like this..
listening thru that song, there were some parts that sounded like there could be like a tb-303 synth bass line behind it..or something of that nature... I know in FL Studio, they have the TS-404 bass synthesizer..That mixed with the 3xOsc can produce wide variety of sounds..
the actual bass sounds like maybe a filtered square wave ran thru a gate effect, which makes hit..drop down...hit...drop down..might even be a saw wave layered in there too.. and perhaps some pitch modulation to give each note that smooth rounded sound
I'm still learning all this stuff myself, so others here might be able to share more info/advice on how to create the sound.. But try messing with some of the things I've mentioned, I think you'll get something similar