I agree with the Ace - it may seem like a lot, but it pays for itself in reduced aggravation. That translates into using the tub more, and getting your money out of the whole package.
Also - most lifts extend the life of the cover by virtue of the fact you are not handling the thing by it ears (skirt, tie-downs, handles, etc.) I said 'Most' because the lifters which pull up on the hinge when closed and hang the cover by it's hinge when open are not going to help a cover last longer. The ones which look something like JohnnyK posted are best, and there are more than one company which produce them.
HTH