With the best will in the world, I would imagine that a prospective buyer would be even less likely to trust an EICR undertaken by you than one undertaken by some 'independent' electrician commissioned by the seller's side.I don't need to pay for the EICR as I can do it.
However, as I said, it's really not for the seller (or a family member) to be organising EICRs - if a prospective buyer wants one, they should organise and pay for it.
Kind Regards, John