Actually, there's a growing scrutiny of the so-called "golden passports" scheme, which has been described by an EU Parliament delegation as risking "importing criminals and money laundering into the whole EU".
However, the selling of citizenship has become a big global market (global industry worth $25bn a year) for wealthy individuals looking for low taxes, elite education or for political reasons.
• Antigua and Barbuda; from $100,000
• St Kitt's and Nevis; from $150,000
• Montenegro; from $274,000
• Portugal; from $384,000
• Spain; from $550,000
• Bulgaria; from $560,000
• Malta; from $1m
• US; from $900,000 invested in a business creating 10 jobs
• UK; from $2.5m