Whatever you use, make sure it has good drainage. Sometimes it can actually be more expensive to create your own mix because you have to buy lots of different bags of ingredients and combine them together. Many of the nurseries in my area now carry an inexpensive citrus/Tropicalfruit container mix that is fast draining, the correct pH and also has lots of added organic amendments like worm castings, kelp etc. Try talking to your local nurseryman, they can probably recommend a less expensive mix that will suit your needs.
Simon