custom search in drupal for custom content type page
As far as I understand you made 80% of the way.
I think you can do the following:  


Add contextual filter to your view so you will be able to filter to results according to the zip code  
Use your custom module (if you don't have one, this will be a good time to create one) to define a custom block (use the following hooks - hook_block_info and hook_block_view)  
Create a custom form that will contain the search box and the submit button  
Make a custom submit handler that takes the field value (the zip code inserted by the user) and loads the views page with the inserted zip code (the contextual filter we defined in step 1 will allow it)  
Place the form in your custom block and place that sweet block in your homepage  


References:
Create custom form

Edit:
By the way, the first comment is exactly what you need.  

   function my_module_my_form_submit($form, &amp;$form_state) {
    $first_name = $form_state['values']['first']; 
    $last_name = $form_state['values']['last'];
    drupal_goto("/my_view/".$first_name."/".$last_name);
}


Hope that helps..
Rotem