I am trying to find out the best place to purchase a keyless entry kit for my 2010 Mazda3 Sport?

 

Im doing the same thing with my 3i Sport. Commander makes a Power door lock kit for $44. and you can add keyless entry and alarm also. Its a plug and play kit for the alarm and the modules look fairly easy to install for the additional equipment. Just do a google or amazon search for the products. Ill be installing/ordering mine next month.