Can the $10 TV-Computer connect to the internet? In fact, this has already been done in the past, according to this article from N-Sider: NintendOnline

More information on the Famicom 'Internet'
Famicom Modem

India's Reliance Telecom sells a phone for $12 (rs480) that receives 2.5G data. I believe this is at cost, but not subsidized. So if you remove the screen and battery, you might have a wireless transmitter for less than $5-8.

Here's some info on hacking a mobile phone to send data to a computer:
http://www.gae.ucm.es/~padilla/extrawork/mobile.html

Alternatively, we could use an existing phone, since many phones have data pin-outs at the base of the phone. Ideally, a phone could plug into the machine to enable data access.

Use a <$10 IC Modem and plug a 1/16th inch headphone jack into any mobile phone. This way the computer could transfer data over the phone lines at >28kbps.

Many families like to have a 'home phone' in addition to personal mobiles (even in the low income brackets). This could be a design consideration.

Alternatively, we could focus on Bluetooth, which is certainly cheap enough.

1. Install Flash Memory on the cartridge
2. Build connection between the wireless datasource and the Flashmemory
3. Ensure that the format is readable by the TVC

Such a system should enable:
1. Programs and data to be sent wirelessly, stored on the flash memory, and subsequently played back on the computer.
2. User data to be stored on the flash chip and subsequently sent wirelessly.
3. Real-time networked data access, with a cache.

The cost of GPRS data last year was about 5p/10kb (12.5 cents per mb - but this might include a monthly data charge as well, as high as rs200). Considering that an entire program on a z80 is usually less than 2 mb, the data rates via GPRS or CDMA seem affordable by the target population. The other types of downloads would likely be text based, so again, this is pretty low cost.

So the question I'd propose is how to write data from GPRS or Bluetooth to Flash memory in a format that is readable by the TVC. Then, equally as important is the question of how to enable the TVC to read and write to a flash memory chip.