Concrete tiles are made from cement and concrete materials. Since these are easily produced synthetics, they typically cost less than clay tile. They offer some of the same advantages and can be coated with a variety of protective finishes. These finishes may be able to provide the same rustic red color that clay would have given your house, if the style is important to your plan.
Slate is a type of natural stone. It may be more expensive than clay tile unless you live near a source for slate, in which case the slate option may cost less. You should also look into fiber-cement tiles that imitate slate; these are even more cost effective. While the fiber version is not as durable as real slate, it does provide insulation.
Asphalt shingles remain the least expensive roofing option. If you need clay or clay-like materials on your roof to protect against the heat or meet strict fire protection regulations, you will probably need to use a different type of roofing material. But if these are not major considerations, asphalt tile will be much cheaper than clay, and more contractors have experience working with the material.
Choose a Plain Style
If you do need clay tile and find it difficult to accept any substitute, try to find a plain style. Clay roofing materials come in many different styles based on roof designs from around the world; some can be very intricate and costly. You may be able to switch to a plain tile style and save a considerable amount of money while still keeping your clay roof.