My hoods never come off my lenses. I like the added security and when hiking etc., it helps keep stray branches and stuff from rubbing across the front element and potentially scratching it. My UV filter stays on all the time but my polarizing filter is not used very much (although I should use it more for landscapes etc).
Hoods can normally be bought for about $25 depending on the lens. The link you provided from Amazon for your lens shows a hood that sells for $13. What were you aiming to use the filter for? Like Kayamedic said an ND filter is nice for shooting in brighter conditions and will help you get nice smooth waterfalls etc. A graduated ND is good for landscapes etc but they are by no means necessary. I bought my UV filter for my 70-200 more to protect the front element. I have a circular polarizing filter I use on my 24-70 to help make the blues pop in skies and reduce blown highlights from reflective surfaces, but I don't honestly use it that much.
In my opinion if you were just wanting to protect your lens a bit, I would opt for the hood over a filter. I don't think it would be worth putting on a $100 plus filter on your lens, but again that is just my opinion. If you are thinking of the filter for more creative reasons as opposed to protective reasons, then I get that, but for protection I don't think it would be worth the cost. If you are careful with your lens and treat it right, it should serve you just fine 