So I've made quite a progression, thought it'd be useful for those that might tackle this in the future...
Stock idler pulley
Solution: bought Nuline pulley kit "Hyundai Excel no A/C" as it was the closest I could find to suit my application. It's a 4 ribbed pulley for a 5 ribbed belt and it comes with the spacer just like the stock pulley.
Problem (reversal haha): The new pulley + new spacer does not fit stock adjustment bolt (bore too small). Spacer also needs retangular part cut off to make it "OEM style".
Option 1: Find a bearing with the same inner bore size as stock spacer/bolt that fits the new pulley. Being a 11mm bore size it was unique and had no luck even after going to a couple bearing shops.
Mission aborted.Option 2: Drill the new spacer with 11mm drill bit.
Mission accomplished. (Thanks Ken for letting me use workshop at 5 am lol
The Nuline pulley kit cost me $61, drill bit $16 and belt is roughly $25 just to give an approx. cost guide
Option 3: http://www.fensport.co.uk/Parts/Model_19/Category_1/26 - another viable alternative, direct fit, less muck around
Now all I need to do is find a belt that fits! Once I've found it, will update this thread. Oh and Merry Christmas!