Disclaimer: I'm in Australia and here vitamins must comply with certain regulations. Feel free to read about it: https://www.tga.gov.au/news/blog/how-are-vitamins-regulated-australia

I bought vitamin D the other day, and couldn't help but to notice the price differences, such as:

Brand A: $8 x 300 pills Brand B: $30, x 250 capsules Brand C: $40, x 300 capsules

All had the same amount of vitamin per dose (1000 u). They all had the AUST L label which means they undergo controls to ensure that they have what they claim to have, and that they are made under certain safety standards.

I also buy iron supplements but there is nowhere near this much difference between brands. The only obvious difference was the type of pill, the more expensive ones were gel capsules while the cheap ones were hard pills.

So, are gel capsules really that much better? Is the price difference justified? Are there other issues that could explain the price difference in terms of quality?