You should take measurements of the windows and get cheap curtains. You could also make use of a nice and attractive bed sheet as a curtain. A table cloth could also be tried provided it fits appropriately on the window. For wide windows, you could purchase a wide bed sheet on sale and convert it into a curtain.
You could do all of the above of choose cheap curtains Singapore. The wide number of options would be made available at your behest for a reasonable price. In case, you purchase fabrics with patterns suitable to the existing decor of the home, they could also improve the overall appearance of the windows and rooms.