The Beatles legend saw the 10ft replica of a Gibson Les Paul go under the hammer at London's IndigO2 club on Tuesday night (11.20.07).
It was one of 60 guitars sold at the auction - hosted by rock'n'roll memorabilia specialists Julian's Auctions - and all proceeds were split between Nordoff-Robbins Music Therapy, the Prince's Trust and the Teenage Cancer Trust.
Paul said: "I'm really amazed and very happy that the guitar went for so much and for such a great cause."
The successful bidder announced he would donate the guitar to London's Great Ormond Street Hospital. Ronnie Wood's guitar went for $22,000, while Pink Floyd star Roger Waters' Wall-themed instrument sold for $21,000.
The guitar themed on former Guns N' Roses guitarist Slash fetched $17,000.
Meanwhile, Paul has backed a campaign to stop the closure of his local post office.
The 65-year-old musician has used the Liverpool post office in Lower Heswall, the Wirral, since 1964 and he is determined to save the "vital part of local community life."
His brother Mike read out a statement outside the shop, which said: "This village post office is a vital part of local community life and as such should be saved for future generations to cherish."
"Its 100-year history should not be cast aside lightly. I agree with thousands of local people who feel that everything must be done to save it. Please help!"
