Soil has a cheaper startup than most hydro techniques.
But the losses in yield over the long term will prove to be more costly than growing hydro. When done right, hydroponically grown weed will yield far greater, without any noticeable loss of quality.
That said, it's easier to get better tasting, potent bud in soil. The micronutrients are there, and you only have to keep the soil ph at around 7.0. Easy. If you don't overwater, you can get decent buds. (Don't believe all the grow hype and rumors spread by these commercial nute companies, either.)
If you're a beginner and growing hydro, you need to invest in a cheap ph meter and tds pen (at least litmus paper!) and go 3/4 of the recommended dosage for most brands. That'll be your baseline for adding for nutes, if necessary.
Obviously, hydro needs far more skill and attention to detail. The amount of time and energy you want to invest into your grow should be another cost to consider.
You can see there are pros and cons, anyway.