Try checking out Hadinger Flooring, at 6401 Airport Pulling Road North, Naples - (239) 566-7100. We have had clients tell us they were satisfied with them in the past.
Also, you may want to try Home Depot, we remodeled a rental condo recently and found very inexpensive yet decent carpet there. The tenants are very happy with it, and so are the owners.
Hope this helps!
Angie Curkovic and The Curkovic Real Estate Team