Mugen shock oil can be bought fm Concept hobbies at Commonwealth. Most RC shops listed in the Singapore thread stock other brands as well.
Different brands uses different measurements. Some go by "cst" while others use "wt".
I doubt u're going racing in tht buggy. U can just get oil ard 450wt or ard 40cst. A bottle is enough for 4 shocks.
Make sure u check out YouTube on how to fill shock oil in yr shocks.
Prices differ so go check out yrself. A bottle is abt 10.