I got cuttlebone for the pure calcium, and osteoform to use 1-2 times a week for calcium/D3. I'm finishing off Leopard Gecko Dust for a multi-vit, then I'm switching to something else.
If you place a small dish of plain calcium in the cage the geckos will eat it when they need it. This "could" help balance the Ca ratio. I think I remember seeing a thread that listed the Ca ratio for different feeders. I believe crix had the highest phosphorous rate.
High Phosphorous ratios are not good for nocturnal, insectivorous reptiles, although I do not know what the 'ideal' Ca ratio is for leopard geckos. I know that high Phosphorous blood levels are associated with renal failure and gout, as well as MBD.
Here is an excerpt from THIS ARTICLE by Dr. Douglas Mader:
"The more important additions to calcium supplementation combinations are phosphorus and vitamin D3. For adequate calcium absorption and bone incorporation the calcium to phosphorus ratio should always be between 1.2:1 and 2:1. Theoretically Vit. D3 combinations are only required in nocturnal species such as Leopard geckos (Eublepharis macularius) which doesn't have UV requirements. Calcium/Vit. D3 combinations are obviously more expensive than regular calcium supplementation. Where correct UV lighting are supplied dietary Vit. D3 precursors will be converted to vitamin D3 and only calcium need to be supplied."