How about writing, tutoring, or some other part-time self-employment of that sort? Have you any interests/hobbies you could parlay into a little business?

My husband and I usually only had arguments of the type you mention when I wanted something that he felt we couldn't afford. I would sometimes rearrange "my" expenses to make that work (I use to buy $100-$300 worth of books from Amazon each month, for example, and I'd drastically cut that back for several months).

Have you an accountant or financial advisor who could look at the situation as a third party and advise the two of you together?