I recently read an article which indicated that transaction costs for US property average between 9 and 10%. This seems staggeringly high to someone like me who is more used to costs around 2%.
The seller has to pay the majority of the US transaction costs and the largest part by far is the Real Estate Broker fee which is typically 6%.
Similar costs in Northern Europe are between 1.5 and 3%. Other overall costs are pretty comparable and consist mostly of taxes and legal fees.