>>402245331
If you're buying the base stations you might as well get the Index. The HMD itself isn't that expensive. That said if you want to spend less than you would for an Index there are basically four options:
1) Wait for Pico 4 reviews and see if it's good, accept china into your house in the process.
2) Reverb G2, good optics, mediocre tracking and bad controllers.
3) Get a Quest 2 (particularly if you value wireless too), which remains good value. 
4) Wait for PSVR 2 and see if it's Steam VR compatible.