Sell one item with q.ty 2 or multiple

I am building a furniture store and the chairs have to be sold in a quantity of 2 or multiples (4, 6 etc.).
One obvious solution would be to build the item as: "Two chairs" so that q.ty 1 = 2 chairs but it must be too easy for my customer to accept ...
Another solution would be to create an option but the shop already has many and many.
I have searched for an extension but could not find a suitable one except maybe this one: http://www.opencart.com/index.php?route ... ity&page=2 which however seems to have issue when used under a language different from English.
Is there a way to implement this, maybe using a PHP script?
Thanks,

Paolo

I don't see why the first option is not viable? Why can't you set up option drop down for the number of chairs 2,4,6 ?