Just painting alone only for ceiling + walls :-

Bangla low-skill : RM1,000
Bangla good-skill : RM1,500-2,500
Indonesian : RM3,000-5,000
Chinese : RM6-10,000

Add 5-10% more if you are changing color that requires an undercoat.

Depends how picky you are and how good your eyesight is.

But between an Indon vs Chinese minimal.

Between cheap bangla vs Indon significant difference.

Paint runoffs, irregular coating and missed spots are common issues when you get cheap ones, also if one wall will be different color you can expect to see some differences. Painting the ceiling?? Definitely plenty of differences. Have areas that you don't want any paint to spill on?? Oh yes you can bet your last RM there would be differences.