The Centre for Information on Language Teaching has investigated seven different ways of teaching languages at primary level.
It found that even using the cheapest model - where the school aims to develop pupils' awareness of other countries and teach just the rudiments of Spanish - cost around pound;4,000 a year.
Dr Lid King, director of the centre said: "This model did seem to us and those that we consulted, including colleagues at the Qualifications and Curriculum Authority, who carried out their own feasibility study into primary languages - just about the minimum viable model for introducing a valuable experience of language learning."
The organisation looked at existing good practice. It found working together was a way of cutting costs. A partnership between a secondary school with a cluster of six primaries where each primary class had a 30-minute lesson a week from their own teacher, whom the seondary helped train, costed pound;12,240 - around pound;1,700 per school.
About one in five primaries already does some language teaching. But the Government wants all children to have an "entitlement" to learn a language at primary level by 2012. In a consultation document, Language Learning, published in February, it ruled out making languages compulsory in primaries due to the shortage of trained teachers.
Details on how they will be introduced should be announced by the end of the year, as part of the National Languages Strategy.
Teachers and language experts have welcomed the proposals to introduce primary languages, but are fighting plans to make languages optional for GCSE students.
The guide to introducing primary languages is at www.cilt.org.ukprimarycurricular.htm