Help with multiple product flavors for one order

I am looking for a solution for the following problem. I sell mini cheesecakes in a box where the customer can choose any combination of our current flavors. The individuals are not products the customer can purchase online singularly. Below is an example of what I am trying to do before I commit to switching to Shopify. Any ideas? I would prefer a solution that does not call for an app that costs have the price of the monthly Shopify subscription.

Thanks in advance. Mike

www.sweetiescheesecakes.com/custom4pack


Custom 4Pack.jpg

I don’t mind paying for a premium web site/ecommerce solution, as a matter of fact, I need it, however, some of the apps I have seen that are addons, like BYOB, are $20.00 a month, which is half of the monthly rate for Shopify if I pay yearly. I think many of the addon apps that do things Shopify should do organically are well overpriced and should not be a subscription service as well.