I believe BSL is asking you to consider a mobile broadband solution, such as the (approx) $60 / month services offered by Sprint, Verizon, and others. These services require a device which generally plugs into your USB port, or your Express port. However, the easiest way to share this type of connectivity is not to use a PC.

Rather, many companies make devices which can accept a mobile broadband device and output a Wifi signal. The CradlePoint CTR-350 is one such solution.

On the down side, DSL is wired and (for most people) more consistent. You're highly unlikely to get as fast of a speed using these devices, and you'll pay more per month, and you'll have to make a 1 or 2 year commitment.