Walmart has the Brinks Interior Non-Locking Passage Ball Style Doorknob (4 style options) on clearance for $7 with free shipping with Walmart+ (30-day trial) or on $35+. Also on clearance: 

• First Secure by Schlage Deadbolt and Keyed Entry Hawkins Knob for $15
• First Secure by Schlage Deadbolt and Keyed Entry Rigsby Door Knob for $15