The use of such a personal bibliography management product is likely to be an investment for at least a few years, if not for your professional lifetime. The amount of money to be spent in purchasing such a tool should be regarded just as an investment. But money can always be a problem and it could orientate your choice towards free or extra cheap products. Do check prices and purchasing conditions then.

Web based products and site license can make 'free' the product for members of the licensed community (academic/school staff, students ...) but not for the insitution itself that will have to pay a probably heavy -globally speaking- fee, thus offering a tool and a service to all its registered or affiliated members: check this possibility with your dedicated Institution's staff.