Thanks for the response. I've actually checked the on united.com and the fare is that much cheaper for the exact same flight on a lower fare class. My ticket is a restricted fare and since its not an international flight - upgradable fares is not an issue. Actually, when I do the change itinerary link, it states that I will save that amount and would I like a voucher sent to my address and not the travel agency.

Just wanted to know if anyone has done this before? I guess I'll just call united.