VRT will be calculated on whatever Revenue decide it is worth here, and that will generally be way more than what you pay for it. If it's from one of the main manufacturers, you may be able to find it in the revenue website to get an estimate in advance. you will also be required to pay Customs & VAT, if buying from a dealer, you may be able to arrange buying it ex-VAT for export.
I hear more people are buying from Germany now, some using a couple of specialist dealers here to help source them.