Here's the best part. I keep the cost low by using two very inexpensive methods of communication - email and postcards. I use email whenever I have the prospect's email address. The cost for email is close to zero. I use postcards when I don't have the prospect's email address.
Postcards provide another benefit in addition to the low cost.
If you don't already have your own house mailing list, start building it today. Keep expenses low by using email and postcards to communicate with prospects on your list. You'll soon discover that a house list is a very cost-effective marketing resource that adds substantial profits to your business.