Wireless network over 3 miles NLOS

I am in deperate need of DSL. It is not available in my area but I have worked out a deal with someone who has it about 3 miles away. Problem is that there is a small mountain between me and them.

What would I have to buy to get reception (at a decent rate, low latency, high transfer).

I found several devices that claim to work at that range but I'm not sure if they really will, AW900x - Outdoor Wireless Ethernet Bridge<br>Non Line of Sight (NLOS) on Sale $959.00 1-800-975-4743 USA is one of them. If I were to buy that (or some other device) would I be able to get signal without putting another antenna on this mountain next to me?

I would appreciate any help more than you can imagine.