All my signed stuff such as Bowie Art stuff and a competition prize I won of a signed Roseland poster were all professionally framed. Each including non-reflective glass cost approx $60 to frame them.
You can cut the cost by using plain instead of non-reflective glass, or you can buy a much cheaper ready-made clip frame but these are expensive for larger sizes.
Personally I would never consider laminating because of the risk of creasing if nothing else.
It depends on you.
My philosophy is that these things should be on show. Sure it would stay mint and more valuable vacuum packed at the bottom of the wardrobe but what enjoyment do you get out of it then?
I then chose to get them looking as best I could by getting it done professionally. (And I got great deals by doing more than one at a time)