This is certainly very common at all the events we go to, people ask all the time for free prints. Recently someone want to take some of our samples for free, as they recognised someone in the photos from a previous event!
My take is always that I'll give event organisers some website sized JPGs for advertising in return for booking us to attend an event. These are generally photos that other people have ordered and that would be processed anyway.
I'd never give someone a free print just because they ask for it unless the circumstances were exceptional. It sets a precedent that is difficult to negotiate out of. It also give the impression that the print itself is easy and very cheap to produce, which may or may not be true, but that's what people assume if you give stuff away. All that does is further de-value photography in their eyes, which doesn't help future sales.
Unless you absolutely need this person for you continued business survival I'd send him a polite message along the lines of
"Although I can supply small electronic images for free, the costs associated with editing, preparing for print, printing, checking, packaging and posting a physical print mean that supplying paper products for free is not possible. A smaller size does not materially reduce these costs, and distributing free prints too all my event clients would reduce my profit to unsustainable levels."
I'd attach an electronic copy, the same size and quality as the ones you provide the club for we advertising, including any watermark if you mark the others.
That way you have done something for him, and if and when anyone asks why he only has the small low quality image he'll have to say because he didn't want to pay £7 for it...
Excellent shot by the way
If that was my son I'd pay good money for a print.