I have seen speculations on this site as to how much Harry's broom actually would've cost him if he'd decided to buy it. Some say a thousand Galleons, others much more than that. Is there any specific information regarding the cost of the Firebolt? If the Irish team can afford seven, it couldn't be that high(Although, they could afford expensive brooms, being an international team).
We don't know from canon. All we know is that Irish and Bulgarian teams each flew them, which doesn't tell us much.
None of the interviews on Accio-Quote mention anything. Nothing on JKR's Pottermore article aside from nebulous "a costly broom".
We also have some estimates, but they all came from Harry's guesses and he didn't know the price! So his guesses are kind of useless.
He thought he'd have to empty his Gringott's account to buy one.
Harry didn't like to think how much gold the Firebolt would cost. He had never wanted anything so much in his whole life – but he had never lost a Quidditch match on his Nimbus Two Thousand, and what was the point in emptying his Gringotts vault for the Firebolt, when he had a very good broom already?
He said "hundreds of Galleons" to Ron.
'Who sent it to you?' said Ron in a hushed voice.
'Look and see if there's a card,' said Harry.
Ron ripped apart the Firebolt's wrappings. 'Nothing! Blimey, who'd spend that much on you?'
'Well,' said Harry, feeling stunned, 'I'm betting it wasn't the Dursleys.'
'I bet it was Dumbledore,' said Ron, now walking round and round the Firebolt, taking in every glorious inch. 'He sent you the Invisibility Cloak anonymously...'
'That was my dad's, though,' said Harry. 'Dumbledore was just passing it on to me. He wouldn't spend hundreds of Galleons on me. He can't go giving students stuff like this –'
Then we have Ron's estimate (who also had no idea of the cost)
'So it must've been really expensive...'
'Probably cost more than all the Slytherins' brooms put together,' said Ron happily.
Apropos nothing, Universal sells firebolt replica for $300