With your budget of about $1000 I would skip the side imaging until you can afford to add it. Just the smallest HDS 5 is going to run at least $700-800 and side imaging $500-650. You can get an HDS 7 for about $1300+ then add the side imaging at a later date. None of the prices include installation.
Humminbird 798s were on sale at wholesale sports awhile back (maybe still are) they were closer to or in your price range and included side imaging.
Hope that helps.