Sales is generally a labour intensive area in business, and you do not want to skimp on perceived customer service.
One way to reduce your sales costs is to look at the accounting and point of sale software and hardware you are currently using. Are there cheaper alternatives, such as moving to outsourced or cloud based systems?
Another way to review costs is to do a very thorough review and analysis of your sales practices and costs. What activities are bring in the greatest revenue for a given unit of expenditure? Are there any parts of your sales activities which are actually not paying for themselves? You want to make sure to focus your sales efforts on activities that are proven profitable and eliminate those which may not bring in sufficient revenue to justify the expenditure.