A second class stamp costs 36p for a letter up to 100grams (as of 30th November 2011)
The cost of a Royal Mail first class stamp is 60p. The price of a Royal Mail second class stamp is 50p. A first class large letter stamp is priced at 90p. A second class large letter stamp is priced at 69p.
.60 cents for a first class stamp. .50 cents for a second class stamp.
1st Class Large Letter
In the UK a standard first class Royal Mail stamp in December 2013 is 60p.
First class mail would be sealed communications. Second class mail would be publications. Third class mail would be advertising and junk mail.
The last price change was on 6 April 2010. The current 1st class stamp prices are: Standard Letter class 41p. Large Letter class 66p.
Second class post
You can find all of the current stamp denominations on the Royal Mail site, here is a link: http://www.royalmail.com/portal/rm/content1?mediaId=52300716&catId=600025 Standard bright blue 2nd class stamp is worth 30p Large letter bright blue 2nd class stamp is worth 47p Standard gold 1st class stamp is worth 39p Large letter gold 1st class stamp is worth 61p Happy Mailing :)
In the UK the Royal Mail aim to deliver Second Class post within two working days.
The Royal Mail promises a piece of mail with a first class stamp to arrive the day after it was send but this may not always be possible. They do not guarantee 24H delivery.
According to the US Postal Service, what used to be called "Second-class" mail is now classified as periodicals: magazines, newspapers and other publications.
The price of a 1st class British postage stamp, for domestic use, starts at £0.39 or $0.64 (approx.). You can check out the exact cost on the Royal Mail's website which is linked here.