You can try winning. They have some cheap jackets. The trick is layering. Layering is so that when you are warm from your trek or whatever, you can take off 'layer by layer' so that you will always lose the 'correct' amount of heat in order not to sweat.
I climbed the rinjani(about 2-5 degrees with STRONG wind) with about 4 layers. 1 thermal wear(those white colour 1), a shirt, a fleece and a windproof, water-proof outer shell.
It suffice for most of us climbing the mountain. Of course, I am physically exhausting myself for the trek, therefore may need less layer.
The total cost of all the layers is about $60 excluding the outer shell which i borrowed from school(but that's by the most expensive layer).
You can check out this traveler store at Marina Square I think it's called explorer.