Please don't give up. You've done so well, and it seems that you're already 2/3 of the way to your goal.
I found myself thinking (sort of 'drifting' or more apathetic about things) around the time I got beyond the half way mark. I was starting to look much better - felt good - was receiving compliments, etc., and was bored with the whole dieting situation. But decided after more reflection to keep 'keepin' on' and here I am - 5 lbs from my goal. You can do it too.
As we lose weight there is more estrogen being secreted from the fat cells that are shrinking, and it's flushing around in our blood stream. It affects our moods and can make us emotional - or depressed. I've read here of many others who have experienced this. If your depression is becoming severe, by all mean seek out some professional help - but keep the diet going as well.
As to the cost factor? I and many others here have lost most of our weight while using alternative products. The cost savings have been very significant. At least half the cost, and often more. There are lots of good alternative products available, you just have to compare nutritional values with those of similiar IP items. In fact, if you have a look at my blog (link below) you'll see that it focuses on helping those who are exploring the alternative route. Maybe it will help you.
There are also several threads here were posters compare and critique/evaluate different alternative products. Very, very useful information. Here's a link to the most 'alternative' thread, and it contains a couple of other links to earlier ones.
http://www.3fatchicks.com/forum/idea...phase-1-a.html
If for whatever reason you decide that IP is not the dieting program for you, please phase out properly so you give yourself the best foundation for maintaining your current weight loss... and don't give up on your overall dieting effort. I really believe that if you do, it will just be another source of dissatisfaction and depression for you. Whereas if you keep working towards your goal weight it will give you focus and a feeling of accomplishment.