Get your current nmol/L value and decide based on that data.
In Germany, you have to pay around €30 for that test. It's not covered by insurance for some reason. Anyhow, if they ask for significantly more than that, they are ripping you off.
edit: Just having checked I misread the dosages completely. Right now it's much less.
Multivitamin - 400IU D3 Supplement - 400IU
Get your current nmol/L value and decide based on that data.
In Germany, you have to pay around €30 for that test. It's not covered by insurance for some reason. Anyhow, if they ask for significantly more than that, they are ripping you off.