I am a vote against this being worth the money. Here was our experience:
Last year we went with our 5 and 2 year old. We were on a budget as well but decided that for the experience we should do a princess meal. We chose a breakfast (most economical option) at Akershus (Norway in Epcot). We were extremely disappointed. Now, I think our girls enjoyed it, but it is not an experience they raved about. We thought our in park experiences were vastly superior and much more personal. We had saved especially for that meal (which even for just a breakfast was NOT cheap!) and I felt like it was a waste of our money. I completely understand that this is not everyone's experience, but IMHO your interactions at the park will be more than sufficient. Have a wonderful trip!
ETA: We never waited more than 20 mins to meet a princess. And the time spent was worth it. I don't remember if you mentioned how long you'll be enjoying the parks, but if you will be there for several days I think it's worth it to save the money and see everyone in park. If you feel your time is limited, perhaps I'd consider a bit more. Regardless, we felt our girls did not receive much value in terms of personal interaction and we likely won't try again.