Any money made from disposal goes back to the Treasury, it's not given to the MOD. Why would the Treasury be interested in second hand aircraft?
Because it could save the Treasury hundreds of millions later on down the line, the money all originates from the same pot. £112m is small change, the government spends the same amount on London weighting and allowances for their staff each year.
If various government departments are unable to join the dots, it's no wonder the country is skint and much mil kit is decrepit and unfit for purpose.