Buying index is better, but their is one thing. The amount of He-index % you have will dictate how many vouchers you get.
So even if you buy a good amount of index, but overall the % share doesn't increase, you will not be benefited.
say you have 100 Index and its 0.005% share.
You bought 100 more. But overall 1000 more were bought by bigger whales, that will have an affect your % share.
I may be wrong though.
RE: Is INDEX The Most Cost Effective Way To Get VOUCHER?