Since the production area will be air conditioned, you need to consider heat sources. If you have some equipment with a high amount of BTUs released, you may want the high ceiling to keep the working area cool and exhaust the heat (don't forget the air has to be allowed to come in to be exhausted out). There are many factors which affect the specifics in your evaluation. For example, it is obviously less expensive to cool the lower 10 ft of the production area than the whole 30 ft tall space. However, the location of the facility may be more of a factor. If you are in a climate which is only hot 1/3 of the year, and the equipment doesn't give off much heat, you may want outside air to be brought in and only use the air conditioner as needed.
To evaluate the cost savings in power consumption, a/c unit size, etc. vs. the cost of putting in a suspended ceiling, you can use a cost estimating book for construction and even some material costs (realize it is very general), and compare it to a cooling load calculation with and without the suspended ceiling. There are many computer progarams to do cooling loads. This is a general answer, but the specifics will have to be addressed by someone closer to the project that has knowledge in this area.