Pre-Op Diet

You know, I read a lot of postings from people whose doctors have said it's ok to eat 1 meal the last 2 weeks. My doctor prescribed a clear liquid diet for the 2 weeks prior to my surgery - which I have started. He said protein drinks, clear liquids, broth, sugar free jello, extra. NO food at all!

But I have a budget problem and have been buying slimfast shakes with 10 mg of Protein &, at least, 1 high protein drink daily. My concern is the carbs in the slimfast, but I cannot afford the high priced protein drinks 3 times daily as I am on a fixed income and I figure I am still getting less carbs than I normally would.....

Plus, since protein drinks have skim milk in them, why can I not get a large jar of high protein powder and make me skim milk protein drinks that way. But they specifically mentioned no milk?? I do not understand why when it's in the pre mixed drinks. Can anyone offer advise concerning this. I just started my 2 week liquid diet yesterday and am looking for a cost effective way, on a fixed income, to get enough protein.