Found these mx5 diff poly-bushes, which are a bit cheaper than the autolink version posted by ozzy:

http://www.strongflex.vot.pl/index.php?page=shop.product_details&flypage=flypag e.tpl&product_id=992&category_id=434&option=com_vi rtuemart&Itemid=1&lang=en

You still need to use the big washers, but you have to strip the rubber off them, which means you can tart them up with a bit of paint ;)