Use 1-tetradecanol (myristyl alcohol). It has a melting point of 37 degree Celsius. Easily available from Sigma Aldrich

Res. Rep. Fac. Eng. Mie Univ., Vol. 29, pp. 31-64 (2004)

PDF will be helpful

Dear Veeramanikandan,

I suggest you the following attached papers. They are useful to answer your question.

The cheapest phase change material (PCM) with a reasonably low melting point would be paraffin wax.

Hope this helps answer your question.

Professor Yehia Khalil

Yale University

USA

Dear Veeramanikandar

As Dr. Yehia suggested, paraffin undoubtedly fulfills all the merits that you expect. Nevertheless, low thermal conductivity is a  major challenge in the real game, say heating ventilation and air conditioning.  

This paper presents analysis of plenty of phase change materials commercially available. See if this helps:

https://www.researchgate.net/publication/267047081_Selection_and_performance_assessment_of_Phase_Change_Materials_for_heating_ventilation_and_air-conditioning_applications

Article Selection and performance assessment of Phase Change Materia...

The one phase change material most readily available and low cost in India are organic ones while paraffin would not stand effective as it’s not available in India and needs to be imported. You can contact www.pluss.co.in for inquiries and samples.

If a melting temperature of 29 degree Celsius is not too low for your application, calcium chloride hexahydrate could be interesting for you: melting enthalpy approx. 190 J/g, costs below 0.50 €/kg using technical grade calcium chloride.

Myristyl alcohol has a melting point of ~37 degC and quite high latent heat (as high as 235 J/g for pure PCM samples).

I would suggest paraffin PCM as opposed to salt hydrates, which have very high degree of supercooling. Since you are focusing at mushy phase of PCM, paraffin would provide an ideal solution. You can choose the paraffin at your desired melting temperature.