Home Depot offers the Ryobi One+ 18-volt Power Inflator, model no. P737, for $19.97. Choose in-store pickup to dodge the $5.99 shipping fee. That's tied with last month's mention and the lowest price we could find by $10. It features a 20" hose with on-board storage clip, 2" pressure gauge, and accessory compartment.
Note: This deal is for the tool only; it doesn't include a battery or charger.
Update: The price has increased to $24.88.