I have just received the publication "The Work of the House of Lords" which gives an interesting overview of its activities.

It also contains figures on the cost of the House of Lords and the House of Commons, in total and per taxpayer. From it, I calculate the following costs per citizen:

 European Parliament £1.40 per citizen
 House of Lords £1.56 per citizen
 House of Commons £5.57 per citizen

Even allowing for a margin of error, it is clear that the European Parliament (despite the burden of interpretation and the obligation imposed on it to meet in two places) costs citizens far less than the national parliament, not least because its cost, is, of course, spread over far more citizens.