P.o.p mouldings incorporated with wallpaper on the bedback and wall would be a great option in a constraint budget

And make bedback with end to end cushioning of a room length this will make your room look larger

Hi Yogesh,

You can opt for wooden batten 4-6 inches above the height of your bed back or say headboard. These can be painted with the paint that we use on walls. But proper putty & pop should be done. Refer image 

2-Put on a nice wallpaper above that or keep a simple paint above that your choice.

3-for other wall go for very neat looking shelves or study unit on the end side & media unit towards the door side. Depth 6-9 inches only. & better be open shelves rather than any drawers.