Most cost effective way to attain residency in Europe (by investment)

Hello,

I am looking for a way to get my girlfriend (from Sri Lanka) residency permit in a european country (marriage, studying or working in a company are not an option for us).

It seems to me that the two cheapest option are:

1. Attaining a residency permit in Lithuania by buying a shelf company in Lithuania, or shares in it, or forming one. That seems to cost between 15-25 000 €.
2. Attaining residency in Latvia through by buying shares in a company. The total cost there is 80 000 €.

All other options to attain residency in Europe seem to cost at least 150 000 € and more.

Does anyone of you have experience of gaining residency this way? We are especially interested in Lithuania. The problem is that we don't know which agency or lawyer we can trust in that regard. How would we be able to find a lawyer that we can trust and know is not just telling us something in order to get our money?

I would be greatly appreciate to hear your experience. If there is another cost effective option to attain residency in Europe, please feel free to share that aswell.