Should I get a lens filter, or just stack in photshop?

So I am new to photography and I am wondering if I should get a lens filter or if stacking in Photoshop will be good enough as long as I take 2 different exposures. Like I said, I am fairly new to this and I would love to get sunset and sunrise photos, but unsure if a lens filter is pratical right now. If stacking is possible I would rather do that, just to save money. If so could anyone suggest a lens filter kit that's not expensive? I have a Sony a6000 with the kit lens, but will mostly use the Rokinon 12mm f2.0 for landscape photography