Hey Aaron,
if you want to run a spindle, you forcibly need a VFD because it’s the VFD that produces the frequency-variable, three-phase current. Also, a VFD is a device to be enclosed into a control cabinet. This is because a VFD is a source of heavy EMI and a control cabinet is made of steel so it is a faraday cage, but you usually also have more components, e.g. 24 V DIN rail power supply for relays, and an emergency stop circuit with estop and reset keys. See here for setting up and wiring a VFD, spindle and control cabinet. You also need a spindle cable that is difficult to manufacture at home and should better be bought ready to use. Anyway to set up and wire a VFD, spindle and control cabinet, you need an electrician or an electrical engineer, or at least the knowledge they have. But you can also buy ready-to-use VFD/spindle/control cabinets. Reputable spindle manufacturers always offer this, e.g. here.
If you want to spend $400 for a spindle and a VFD and a spindle cable and a cooling pump and a fully equipped control cabinet, it will be chinese crap. My VFD (Omron MX2 aka Hitachi WJ200) was $400 alone.
Your VFD should at least have sensorless vector control (SVC) and not only stupid V/f control.
Be aware that on chinese spindles, the power rating is often wrong. See here for an example.