SW:TOR is on sale through Origin.com from now until May 6th.
Prices are as follows:
$35 for standard digital edition (normally $60)
$45 for digital deluxe edition (normally $80)
You do not need to have Origin running to play SW:TOR - it uses its own, separate launcher. I would guess that you need an Origin account to make the purchase, but then they will email you a game code which will give you access to the installer.
If you want a trial for 1-week, just let me know.