itch.io

One relatively low-cost thing you can do is find a decent budget microphone and a DAC, and add vocals as well. It's also a great way to blend the virtual instruments together. A good microphone is the Shure SM-57, since they've been used in everything for like half a century, they're very durable, and the sound is accurate. More expensive microphones color the sound in interesting ways, but having one that is very accurate lets post-processing programs have something to work with.

Choosing which instruments are virtual and which are real also helps. All of the instruments in my track are real, but with the drum, I found a large but modestly priced frame drum. I then used a pitch modulation plugin to shift its tone to provide a drone.

Another thing that can help tremendously is a midi controller when your virtual instruments have dynamics, so that you can do the velocity naturally.

Those are, in my opinion, some of the highest impact things you can do to provide some sound quality to your base setup.