PHP MySql help with complex Multiple table Query

I'm storing a bunch of data for communities in MySql

My initial communities table has these fields:

1. id (primary key)
2. name
3. logo
4. map
5. description

I'm then storing different data for each community in other tables like this:

Table: community_amenities

1. id (primary key)
2. community - this references the id field from the communities table above
3. amenity - A comma separated list of amenities that this community has - 2,3,5,7,8 etc - these numbers reference IDs from another table

Table: community_prices

1. id (primary key)
2. community - this references the id field from the communities table above
3. prices - A comma separated list of price ranges for homes in the community these numbers reference IDs from another table

Table: community_products

1. id (primary key)
2. community - this references the id field from the communities table above
3. products - A comma separated list of types of homes in the community these numbers reference IDs from another table

I then have a form with a number of checkboxes that let users choose the amenities, price ranges and products that they are interested in like this:

<input name='amenities[]' type='checkbox' value='1'/>
<input name='amenities[]' type='checkbox' value='2'/>
<input name='amenities[]' type='checkbox' value='3'/>
<input name='amenities[]' type='checkbox' value='4'/>
<input name='amenities[]' type='checkbox' value='5'/>


<input name='prices[]' type='checkbox' value='1'/>
<input name='prices[]' type='checkbox' value='2'/>
<input name='prices[]' type='checkbox' value='3'/>
<input name='prices[]' type='checkbox' value='4'/>
<input name='prices[]' type='checkbox' value='5'/>

so my question is...

I need to grab the items they have selected from the form and query the database to display communities that match the criteria.

I can do it fine with 1 of the fields like this:

$priceArray = $_POST['price'];

$selectPrice = join(',',$priceArray);

$sql = mysql_query("SELECT * FROM community_prices WHERE prices IN ($selectPrice)");

But i need to do it with all the tables and I need to return only communities that meet all the selected criteria.

I've tried a whole wack of different methods (UNION, JOIN) with no luck. Any help would be greatly appreciated.