Was I right??

A bloke won a car I was selling on e-bay and came round to collect this morning.......he said he wanted to hear it running before he paid me and I refused....there is nothing wrong with it but I wouldnt let him out of principle!! He said "just leave me a negative" and walked off

the co*k has cost me £10 fees and wasted my time

Was I within my rights....as far as I'm concerned he had the last 10 days to come and look/listen!!