Conduct an internet search for villa rental websites. There are many options, such as Rentvillas.com, Villarama, or Villarenters. Choose a site that allows you to research villas based on the region of Spain and the price you wish to pay. Enter how long you want to rent the property, how many people will be staying there, and the dates you will be traveling. Look through the results and save the information for each property of interest.
Check tourism sites such as "Spain," the official Spain tourism guide for the United States, or "Spain-Guides." These websites offer information about the various regions of Spain and travel there, in addition to suggestions for booking accommodations. Peruse any results from villa searches through these sites and save the information.
Investigate listings on craigslist.com under the vacation rentals or sublets/temporary sections. While you cannot enter significant search criteria as in the other sites, these listings are directly from the people offering the villa rentals and may not require booking fees as some sites do. Contact any of interest in your price range to get more information.
Pull together your saved information for properties of interest and compare prices. Choose the one with the price best suited to your budget. Depending on the website used for finding your top choice, your method for booking the property may vary. Have your credit card available for sites that require a deposit online.