I didn't bought anything in steam sales in ages, since they changed Poland regional pricing to same as Germany and UK (countries with 5 times more median wages). I love (/s) how the games with -50% sale still cost the same as new games before pricing change and sales are usually 10-35% now. But i guess that was deserved prize for successfully reducing most of piracy in Poland.

but looking there, some worth playing:

• Symphony of War, strategy not RPG, but damn good one in the old style, price is decent
• King Arthur: Knight's tale, also more strategy than RPG and also very good, price is ok-ish but i wouldn't buy
• Pathfinder WoR, was in Humble month ago or so, so the price isn't very appetizin, but i guess worth it if you missed
• Dragon Quest IX - would be great game but PC port have traditionally borked controls, like really frigging borked
• X-Com 2 -95% lol still best game in genre after 8 years
• Atom RPG - poor brother of Fallout, but if you want to shoot AK-47 and exorcise evil spirits with the name of CPSU, the price is good
• Encased - rather B-class but good rpg and for good price. Was free on Epic some time ago tho