8Mbps power line communication with PLC \ Homeplug
The problem is the other way around: most of the general public doesn't want to buy homeplug compatible modem IC's and so most of the IC's are restricted to manufacturers like broadcom\qualcomm who mostly deal with higher volume customers. (Like the BCM30321).
Look for homeplug IC's and IEEE 1901 which is the standard. Homeplug (the not green version) goes to 200Mbps. (also the 200Mbps is assuming a good pathway, which is not always the case with home/commercial wiring and YMMV as this rate is negotiated and depends on the noise on the lines and distance between devices)
There are also some non monolitic IC options here
To actually implement a product around one of these IC's would probably take 2-3 people just because of the time and effort it would be a lot to take on.