Both Padini and G2000 are having a promotion of 2 shirts for RM129 right now. Quality wise, you should get the G2000 as their strings are not flimsy like the one you find from Padini's.

G2000's available colours are all plain, with an array 4 types from each tone of purple, blue, pink and grey. Padini however, have different types of colours and design.

All good for skinny body (unless you're super skinny, try the 14 1/2 size from G2000).

Well you can always opt for Topman's plain shirt with contrast buttons at RM119 each currently.

For trousers, get the 1 from G2000. Padini's trousers, although being slim-fit, it still looks fat due to the soft fabric they use and they have very very deep pockets. Well, it will be good if you're super tall or you have long arms

Cotton On selling cheap distressed shirt, somewhat looks like chambray, for RM50. Something like this

Esprit/EDC selling shirt for RM99.90 when on sales, Zara selling for RM139.90, Topman and so on. You just have to look around.

I saw 1 blue casual shirt from Seed Pavilion, not bad looking.

Erm you are at the wrong thread to ask, but you can get 'em at Topman or Zara.