R410A is not freon - Freon is R22, just for clarification. R410a goes undernames like Puron, Florane, EcoFlour, Genotron, etc and is replacing R22 as it is phased out and R410a and similar based systems are being installed.
Excellent question, with as many answers as there are answerers. In bulk (25 or 100 lb canisters) currently runs from about $3-10/lb on the low end to as much as $40/lb depending on where you buy it, and HVAC contractors charge customers typically from $25-70/lb. Even though it is less than half the price in bulb as Freon (R22), its price has been rapidly increasing as contractors realize they can charge what the market will bear - and people have gotton used to $50-100/lb for Freon, so R410a is creeping up to the same range. I saw one 25# canister sitting around at a shop the other week that still had the distributor label on it showing $85 cost (so about $3.50/lb), technician said it was being charged out at $140/lb plus labor !
Bear in mind some contractors wrap the labor for gs recovery (required by law) and recharging into the gas cost, and some charge separately from $100-300 for the labor, so that clearly affects the final cost.