Mixed case extension

HI,
Does any one have an extension which will allow a case of 12 bottles to be selected from any of 50 different manufacturers and put in to one "case" which then has a fixed price say £35 per case plus carriage say £9.50

we have a site which does this already but is written entirely in PHP and is very difficult to update or alter.

The site is http://www.cornish-bottled-beer.co.uk/ and the new open cart ( just getting started).. is
http://www.cornish-bottled-beer.co.uk/opencart/

If any one can suggest a way we would love to hear
from you.
Kevin

Not sure if this is correct. You might want to take a look at this: http://www.youtube.com/watch?v=ZSxv20fSUU0

It allows you to buy X products within the same category at X price

NO not quite what we need
The selection of 12 products (in a case) needs to happen before the one item (the case) is added to the Cart.
Ie
Select any product from the products list
add up to 12 to a Case.

Add the Case to the Shopping Cart which has a fixed price with a fixed Delivery charge.

Then if required repeat the process for as many Cases as needed.

Thanks for the link though..
Kevin

Another thought regarding this problem is .....

Can each product be put in a Group similar to a Category.. but the Category has a price set when you have selected say 12 products in that group?

This would do what we want regarding the select 12 bottles (which make up a case) and keep the pre made Cases of 12 out of this group?

Thanks
Kevin

Probably think I am getting a bit desperate now but ...
I have got this far with using the Options section I have created a product Called Select 12.
Set a price as £0.00 set the options to correspond to the individual Bottles from the store.
if I select the Product then select say 4 options my checkout looks like this
Shopping Cart (0.00kg)
Image Product Name Model Quantity Unit Price Total
Select 12
- Bottle Store : Blue Organic Dark Al..
Select12 Remove £3.17 £6.34
Select 12
- Bottle Store : Maiden Voyage (ABV 4..
Select12 Remove £3.17 £6.34
Select 12
- Bottle Store : Fistral Organic (ABV..
Select12 Remove £3.17 £6.34
Select 12
- Bottle Store : Scuppered (ABV 4.6%)
Select12 Remove £3.17 £6.34

Now all I need is to set a count on the total No of items in the Cart to 12! if not tell the customer to choose some moor.
Ive seen this somewhere but don't know where it goes in the system can any one help?

Just an update with this

I have successfully achieved this by
Creating a Multi-Store
Giving the Cases Store just the Default Template. Sells cases in units of 1
Giving the new Bottle Store a different Template it doesn't matter which one it is, Sells bottles in multiples of 6 12 18 24 etc.

Then in Catalogue/view/theme/"yourtheme"/template/checkout/confirm.tpl
on line 60
I did this
<?php if (((int)$this->cart->countProducts() % 6) ==0) { ?>
<div id="payment"><?php echo $payment; ?></div>
<?php } else { ?>
<div class="warning">You must purchase Beer in cases of 6 at least to checkout <a href="javascript:history.go(-1)" onMouseOver="self.status=document.referrer;return true" class="button"><span>Continue</span></a></div>
<?php } ?>

also there is a bit that is commented our with a redirect which causes this to fail.( line 70 ?) so I removed the comments! and it works fine. Is this a BUG?

the %6
means if the Qty of products in the cart is not a multiple of 6 then tell the Customer to buy some more.

I would like if I have time to put this mod on the Minicart page but if the Cust is loggin it takes no time to get back to the Confirm line once more products have been entered.

Hope this helps anyone in the same boat!