Well, I assume that you are interested in the localized area you serve?

An easy free way could be to have the user go through a simple registration form, then use an iframe tag to an existing site that has the MLS data.

The user never leaves your site, you capture the lead and provide the useful information without having to worry about it. Plus, whatever site you reference gets some additional traffic and advertising so everyone makes out.

I've seen a bunch of sites that use this method.

Cheap option, there are companies (Try Google) that offer a similar solution that is more customizable and brandable.

I've found a lot of MLS options that Realtor's are using. Here are some of them.

http://azhomevaluesat.com/realestat...w/id,4/catid,2/

and of course realestate.yahoo.com is getting unbelievably good.

Rob