A candida overgrowth is a very serious condition and is difficult to recover from; I would put it up there with mono, aids, cancer, etc. as far as its difficulty and duration in recovering from. Plan on a 6-18 month recovery period.
I don’t think vitamins B and C will cure your infestation very much or make too much of a difference; they will make you feel better but won’t kill any candida. If you wanted to save money, you can simply get cheaper vitamins (such as swansons).
Additionally, one bottle of probiotics will not cure your infestation and you will need many bottles of them. I would look into trying out some other strains of probiotics in time such as HMF neuro or megaflora as a comparison. A 12 month supply should cost close to $500 US.
Cleansing only creates a beneficial environment for recovery but doesn’t kill very much candida and won’t make much of a dent in their numbers.
I would not follow the website diet because it is not very strict. They promote eating foods such as beef and pork which takes days to digest while chicken and fish only take hours to digest in comparison. Additionally, you should eat low amounts of starches, molds, and sugars and thus should avoid/minimize items like rice, potatoes, corn, fruits, nuts, etc. while on the diet. The website promotes many of these food items which could set back your recovery. We have a strict forum diet that removes all of the bad foods.
The diet itself is very expensive so I would worry about this just as much as the supplements.
Diatomaceous earth is relatively cheap but you will likely want and need to try other antifungals when it runs out.
If you want to compare your vitamins list to mine; I spend about $500 (US) every 2 months on the diet.