Trust me, it's much better for your cats to adjust to changes in your home rather than in a shelter. Most shelters/sanctuaries are overflowing with homeless cats. They're underfunded, under-staffed and packed. No cat should be in there.
Here are some links to pages with more information on living with cat allergies: http://www.catster.com/kittens/Allergic-to-Cats-How-to-Keep-Your-Cat-and-Your-Health-144 and http://www.humanesociety.org/animals/resources/tips/allergies_pets.html.
Take the necessary steps to keep your pets in your family. Pets are a lifetime commitment. Be a part of the solution -- not the problem.