ZK-TB21 2.1 Channel Bluetooth 5.0 Amplifier Board – TPA3116D2 Chip 50Wx2+100W MAX, DC 12-24V, AUX Input, HiFi Stereo Receiver for Home Theater Passive Speakers Subwoofer, Treble & Bass Control
It's about $1.45 under what it usually sells for. Need it now? Fair price. Can wait? It dropped to $11.00 once — it might happen again, but the odds are it won't. Don't wait around for that price.
Price context
This verdict comes from tracked price history. Run a live check for the freshest read — or set a free price-drop alert.
Run a live price check →typical$11.00
all-time low100/100
Drop Tendency
How we predict: Thrifle reads this product's real Amazon price history and runs it through our price models — a transparent statistical engine plus GOAT Model 2.0, our machine-learning model — to estimate whether the price will drop, how low it's likely to go, and when. Every verdict shows its benchmarks and its own confidence, and we grade ourselves in public: see our live accuracy track record.
Frequently asked questions
Will the price of ZK-TB21 2.1 Channel Bluetooth 5.0 Amplifier Board – TPA31… drop?
Thrifle's model expects it could drop to about $16.99 (likely $12.60–$19.12), typically within about 233 days — versus $18.99 today.
Is now a good time to buy ZK-TB21 2.1 Channel Bluetooth 5.0 Amplifier Board – TPA31…?
Thrifle's current verdict is Good price (Borderline) with 92% confidence. Today's price of $18.99 is at or below the typical price of $20.44. It's about $1.45 under what it usually sells for. Need it now? Fair price. Can wait? It dropped to $11.00 once — it might happen again, but the odds are it won't. Don't wait around for that price.
What is the lowest price ZK-TB21 2.1 Channel Bluetooth 5.0 Amplifier Board – TPA31… has been?
The lowest tracked price for this product is $11.00, recorded on Mar 16, 2026.