Upgrades are $20 Domestic US/Caribbean, and $100 Transatlantic.
For those of us who are single and without a domestic partner, we can have a registered guest (1 for the year) who flies free with or without us traveling. The value of the tickets (using some % formula) gets added on to the employees compensation for tax purposes, but no actual $ up front. We also get 8 Buddy passes a year which are 10% tickets and can be given to anyone.