Was talkin to a rep for Manor Stone to get a quote for limestone for the front of the house and he was saying that the limestone cills were €70 per linear meter, don't know what width it is though for that price, might be worth giving them a call.
Also said that granite cills were €35 per linear meter.
Are the sills being quoted for cut from a single, solid piece of stone- some of the cheaper sills have the upstand (sometimes referred to as a "stool", but not technically correct term) cut as a separate piece which is then bonded onto the main sill section. This is obviously a much cheaper production method. Just something to watch for.l