Looks like as part of the new Starbucks reward programme there is an opening offer where you can get an upgrade to Gold membership for a year after topping up $50 to your rewards card.
- Free drink every 150 points ($75 spend)
- 1 free drink upsize per month
- 1 free drink customisation per month
- Buy 1 get 1 free on food and drink once per month
- 20 bonus points on anniversary dates
- Another free tall drink (on top of signing bonus).
Edit: I saw the rewards programme offer has been posted already but thought this is worth calling out as separate.