The cost of implementation actually depends on the method you select, for example, for someone practicing it subsistently, the Rotary method is a no go area, it is cost intensive.
Another angle is that in the long run, most of the hydroponic systems are more cost effective than Geoponics since they only get cost intensive at the start(for example, you wouldn't need seasonal tillage, or have to practice crop rotation), so over time, you'll reduce cost.