In all honesty....all servers are pretty high cost even if they think they are low. I get that if one server sold books at 400k and aries sells at like 2m-4m, it seems like that server is better.
The main question here is, are you someone who wants to play on your own most of the time? or are you someone who likes to play in a big community? If its the first one, go ahead with Gemini. If its the second choice go with Aries because, even though the prices are ridiculous, it's more active than any other server. I mean, its got 7 seperate servers just to let everyone not get crowded.

I'm someone who likes a somewhat active community but not so active that you see the world chat go up every second. So I chose Taurus. Its like a mini-Aries.