When you finish the main quest line (harborage) and get into the VR1+ area you'll be able to buy VR glyphs.
If you want to buy them while you're still in Coldharbour your only options are:
- Join a VR PVP Campaign and buy them with alliance points from the merchant at the gate
- Buy them off guild traders
- Do any fighters guild, mages guild or main quest lines you still have open and you'll get them as drops since they scale to your level