Are there any inexpensive drip systems for watering raised beds?

Yes..

Sites-Gardeners-Site (http://www.gardeners.com/search?q=aquacorner&utm_medium=cpc&utm_source=Bing&utm_term=%2Braised%20%2Bbed%20%2Bwatering%20%2Bsys tem&SC=XNET9294&kwid=1430a54c7aca4c6f8a454f88c9572c2e)

Drip Irrigation Supplies - Drip Irrigation Products Irrigation Direct (http://www.irrigationdirect.com/irrigation-products-and-supplies/drip-irrigation?utm_source=bing&utm_medium=cpc&utm_term=drip%20systems&utm_campaign=ACE13%3A%20Drip%20Irrigation)

There are MANY choices to choose from.

Home Depot and Lowe's have them and they are inexpensive.