They could involve the broker losing MLS privileges for his office or company because either the webmaster or real estate agent used the data in a way that was against the MLS regs.

This is one reason the MLS in some states makes not only the real estate agent sign an agreement but also the webmaster and broker.




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The Best Real Estate Agents in Las Vegas and Atlanta in the Las Vegas Real Estate Market Atlanta Real Estate Market offering Las Vegas Homes for sale and Atlanta Homes

You might think about using a 3rd party to handle the IDX part, I slapped up my site http://locateAhouse.com and used http://www.ihomefinder.com to handle the IDX feed and it integrates pretty nice with the rest of the site, no frames is something that was a must for me.
Maybe the lower liability having another party handle it would be worth the extra cost, I dunno.