Parts Connexion Has Black Gate FKs listed in 1000uF/50V, which would be an excellent option. They also have 1000uF/25V in the "standard" Black Gate. (http://www.partsconnexion.com/t/catalog/CapacitorsElectrolytic.html) Click on, "Black Gate", at the bottom of the page.
nx 25v 1000uf never was 15usd/psc to end-users as i remember. I could help in yours project but surely with neither 15 or 25usd/psc sum would be option to me. BTW change only critical places- not whole caps you found. hope this helps. good luck in yours project.