I'm trying to find out how to make Shopify give you options on a product page, where you can select various quantities of different elements? For example, on our wedding stationery you would have the entire pack as the product, but then within that you need to be able to buy, say, 60 daytime invites, 30 evening invites, 90 placeholders and 90 envelopes. So that pack is made up of 4 "sub-products" that are priced individually and the system does the maths for you as you add things to the basket. I have had a look for apps, etc, but if anyone knows how to do it without an app that costs a lot (to a small business), I'd love to know.
Your desired functionality can be done using custom collection template and custom coding, I can say that it will take about 3 hours work.
The way is the following.
We need new collection template where we can show one product as main product and the other as options, then the customers can go into this collection, and choose the options, daytime invites and so on, and then clicking on add to cart will add main product and the other products into cart via ajax, and the calculation will be automatically.