Upsell app that takes customer to product page rather than on popup

Hi all.

I've installed 10+ upsell apps looking to find one with a specific feature that I need for my store. I would like an upsell pop up when specific items are added to the cart. I want a discount to be offered for the upsell product but this pop up then needs to direct the customer to the page (keeping the discount).

I sell personalised goods so none of the pop ups I've seen yet will allow custom metafields as drop down menus or text boxes so I'm a bit stuck here. If anyone has any advice, that'd be greatly appreciated.

Thanks