You can purchase one of the three flavours of Stream to 3D below. Scroll down to review each of the options. There are both one-off purchase and subscription options.
If you want to try before you buy, then the first option "Stream to 3D - Real-Time" is for you, as it provides a one week fully cancellable free trial. If you cancel within the first week, then there is nothing to pay. Note that this particular version of the product does NOT provide for video streaming or off-line conversion functionality.
If you want video streaming and/or off-line conversion capability, then you will need either the Complete or Standalone flavours of the product. Complete is a subscription product, Standalone is a one-off cost.
If you would like to see an example of the purchase process before you buy click here: