How much does a hotspot cost

That's something you need to ask your carrier. No one here can answer that.

Different providers have different plans. Some may include hotspots as part of the normal plan features. Some may be an incremental charge.

Without knowing your carrier, your plan, or the features offered, it's impossible for anyone here to tell you.

That’s a question for your cellular network provider, as they do the “provisioning” of the hotspot feature.

Like others said, it depends on the carrier and the specific plan. It may not be an a la carte option. Last year my carrier had a temporary data limit increase in addition to allowing all customers to set up their devices as hotspots, but that was only for a few months.