Nivsy, London has had the Dome, paid for largely by lottery money. The Olympics will be predominantly paid for by lottery money, sponsorships and London taxpayers. I don't buy lottery tickets, I don't live in London, so I'm not going to complain so loudly.
Both of the above over-ran their budgets. Then there's Wembley - I think I might be paying for that one, but I also hope to be able to benefit from a concert or two, and something to brighten up the journey out of Euston.
EDI already has a perfectly good bus link into town. Sure, I'd prefer a train, and I'd find a direct link to Glasgow useful from time to time. But if the ticket costs are anything like the rate charged by the LHR Express (article talks of premium fares), I might still end up using the bus. Unless of course they do what they did at NCL, and scrap the bus. Am I also right in thinking that Edinburgh to Glasgow train journeys will now take longer?
So all I can say in response to your question is that the £610m will almost certainly end up being conservative.
There was no reference in the article about who is paying for this facility, and I assume it won't be BAA. If we're not paying for it, then I'll gladly stand corrected - but whoever is paying for it, I just can't see much sense in the sums.