Sum based conditional sorting

Hello,

I can't seem to find an answer, but it could be that I'm asking the wrong questions.

I have some data with various items that have a cost, and a numeric value. What I'm trying to do is extract a list of items to buy up to a set limit that will produce the maximum combined value. I've managed to get as far as sorting the items based on value/cost, and stopping the list when I can't afford the next item(I left that out for now for clarity), but I can't seem to figure out how to continue past that to the next item I could still afford?

For example in the attached you will see that while I can't afford Item I, I should still be able to buy Item B.

Would someone please help point me in the right direction?

Thanks,
B