Stairs are never budget friendly, and straight stairs always take up more space than a spiral. As soon as you remove these, anything you do has to be fully code compliant. A general contractor or stair builder (you may have someone in your area who just builds stairs) will be your best bet for local pricing and layout ideas.

we tried everything to avoid a spiral stairs to the loft of our vacation home, but what E-H says is true. regular stairs take a lot of room. add to that you have to have headroom at the top so it must land where you dont have a sloped ceiling.

you can abandon your loft..... if its just kind of decorative up there.

What do you have in the loft, IMO there are very few stair designs that save as much space as a spiral