Some years ago I heard on a radio station a plaintive rendition of a
song with the refrain "he only had a nickel but he wanted a dollar
song" I want to know the name of the song and the composer.

Hello Rikardo and thanks for your question.


The name of the song you’re referring to is the Nickel Song by Melanie
Safka.
Source: Nickel Song by Melanie Safka
http://freespace.virgin.net/robert_ian.smith/Comp/Comp057.htm
    
Melanie Safka, born in New York in 1947, is best known for her
wonderful single, "Lay Down (Candles In The Rain)" a 1970 hit, which
was inspired by Melanie's experience at Woodstock. During her
Woodstock performance, people lit candles at a concert for the first
time in rock history.

Here are the lyrics to the Nickel Song.
http://ynucc.yeungnam.ac.kr/~bwlee/lyrics/nksong.htm

Click on this link to hear a sound sample of the Nickel Song.
http://www.cdnow.com/cgi-bin/mserver/SID=583974644/pagename=/RP/SHARE/soundclip.html/UPC=4465996302/disc=01/track=09/source=wmf

Melanie: Beautiful People-Greatest Hits can be purchased online at CD
Now Website. The Nickel Song is included on this CD.
http://www.cdnow.com/pagename=/RP/CDN/FIND/album.html/itemid=771177/from=sr-2235190-2

The New Seekers also recorded the Nickel Song. It is available on
their CD “New Seekers Greatest Hits.”
http://www.amazon.com/exec/obidos/tg/detail/-/B0000246DN/qid=1033011210/sr=1-2/ref=sr_1_2/104-4378052-2131957?v=glance

Additional information that may interest you:
 
Melanie’s Biography
http://www.rockforever.com/singers/melanie/melanie.html

Melanie’s Discography
http://web.inter.nl.net/users/dj/melanie/discog.html

Search Criteria:

nickel song
://www.google.com/search?hl=es&ie=UTF-8&oe=UTF-8&q=nickel+song&btnG=B%C3%BAsqueda+en+Google&lr


I hope you find this helpful 

Best Regards,
Bobbie7-ga

Thank you, Bobbie for a prompt and complete answer, it was more than I expected.