The current fee is £77.50 for the standard service. (£122.50 for the 'one week' service. £129.50 if you make an appointment to attend a passport office for the 'same day' service).
Up until a few days ago I might have suggested that, if you only travel to the EU, you should wait to see if Identity Cards (which are currently only available in the north west of England) have been rolled out across the whole of the UK by the time your passport expired. (If so, you could have used an ID card for travel within the EU at a cost of only £30). However David Cameron has now announced that ID cards are to be abolished,so we've lost the 'cheap option'.
All new UK passports are now 'ePassports'. They look the same as the old passports but contain an electronic chip. The data on that chip is the same as is printed on your passport; nothing else is included.
http://www.direct.gov...ourpassport/DG_174097
Chris