I would offer 230k and in 3 weeks time come back and offer 250k and tell them its your last offer, they have a week to decide.
and what if an identical house down the road has an asking price of €240k? You can't go giving advice on numbers without this basic information.
I've said it before here, if you're trying to figure out what a reasonable offer is do the following:
1. Check asking prices in the area: How does the asking price compare to similar, smaller, larger, better looked after houses
2. Ring the estate agent for a number of houses in the area to see where the bidding is at and how long the house is on the market. The estate agent may even tell you straight off that the seller will accept x% less than asking
3. Check comparative rents in the area on Daft over a period. A good rule of thumb is that the interest you'd pay on a mortgage should be reasonable compared to rents being commanded for similar properties
This is the least you should do in forming an opinion on price. I repeat again, do not take heed of lazy answers