Convertible bonds would still require paying for the shares, right?

Part of the problem is that the shares are too expensive for the recipients of them to just buy them. Essentially, they should have been allocated as initial founder stock but weren't (due to various reasons that I won't go into).

At the moment, from what I hear, stock options seem to be the best way to allocate shares without needing a large transfer of money from the recipients of the shares to the company (or some other party).