Isildur's bane
Super Freak
I'm not convinced this will be cheaper to pick up down the road. I'm having a hard time finding the Morgul Lord at a reasonable price, and Sauron seems to be even more scarce. I scored a Cave Troll artist sample off Ebay, which was just an insane pickup.
I think these LSBs (in all licenses) are more popular than people here seem to believe.
The morgul lord and sauron had half the es of the balrog at 500 and 550 respectively. The LSB's are popular but the high price tag of the balrog and the huge 1000 ES will probably have decreased demand and therefore decreased price IMO.