[michaelthepsycho]

How good are your displays? What resolution? If you're doing 60hz monitors, you can get away with cheap AMD APUs that run less than $300 a machine if purchased in bulk.

If you're doing 75+hz panels (maybe even 144hz) and need GPUs to match, it might go into the $400s. LoL is a very low-demand game, graphics-wise.

Is it a dedicated gaming room? Do you even need cases?

Let me know what your budget is. And, AFAIK, I don't think Riot lets people host because they are a F2P, micro-transaction-based business model. No one would buy anything if you can just mod skins client-side (although many people are already doing this).