If someone turns up to play with counters and as long as it is identifiable which ship is which, then I don't have a problem.
In fact if someone was turned away after travelling all the way to Swindon because they only had counters (even photocopies) then I would walk out on a matter of principle.
This game is for fun, if people forget that and start making it hard for people to play the game (remember, if you can still get miniatures; they aren't that cheap) then it's not a game worth playing!
If people are that anally retentive, then I suggest they look elsewhere and play something else.
Apologies for the rant, but it winds me up when it is suggested that people may be rejected because they can't afford the mini's!