The attempted rescue of the northern bottlenose whale that swam up the Thames boosted the revenue of the British Divers Marine Life Rescue by more than six times the cost of the ill-fated operation.
Volunteers' endeavours to save the whale cost the small charity around £5,000, but the ensuing publicity brought in more than £30,000 in donations.
However, the auction of the watering can used to rehydrate the whale has been hampered by hoax bidders on eBay.
Volunteer Faye Archelle, the can's owner, said the charity realised rogue bidders were involved when bids jumped from £10,000 to £99,000. Volunteers have been contacting bidders to verify their bids - by Monday the amount raised was down to £410.
Archelle said: "I wanted this to be for people to give what they could in a fun way but unfortunately it turned into a bit of a free-for-all."