I'm guessing there's an app which will do what I'm looking for but I can't seem to put my finger on it. This is something I've seen on UK supermarket websites and I'd like to emulate it.
Let's say I've got an offer running where you buy 2 items and then get the 3rd free on selected products. What I'd like is to have a little badge at the top of the product image (ideally) in both collection and product view which says something like "part of our 3 for 2 offer-see all items in offer" with a link to a collection which contains all the products which qualify. It would be ideal if the badge displayed automatically for all products in a given selection.
This may or may not be how supermarkets work in the rest of the world but ASDA in the UK for example both instore and online have a permanent "3 meat or fish items for £10" for products which tend to be normally sold at about £4. Every time I use the site, I end up buying one of the items because it's on my list, being informed it's part of the offer with a product banner/badge and then clicking on the link to see what other items I can have for my £10 total. I guess I'm not alone because they've been doing this for years so it must work!!
App Selly has a bundle feature that can help you to offer buy 2 get 3rd free.
There is an option to add collection link on product badge/label too.