An upsell is a definite necessity. However, I would be a little wary of overkill - there is nothing more irritating to a lot of purchasers when they are constantly taken to upsell after upsell and being told (once they have purchased the original product) that the 'original product' won't work as well if they don't purchase the more expensive upsell!

I know this is a business but I really believe that being ethical and giving people value is imperative if we want to be here for the long term.