Bluetooth protocol: AVRCP, WMA, Material: ABS, FLAC, WAV, TF card/USB disk(Max capacity): 32GB, Frequency stability: 10ppm, HFP, Music format: MP3, Power output: 5V2.4A+QC3.0, A2DP, Product input: 12-24V, Bluetooth version: V5.0, Frequency range: 87.5-108.0MHz.
Go down and check coupons out. Remember to check price history if it is available. Best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. Well, there is one coupon available right now.
Link: Banggood product page
1. ($17.18): BANGGOODSD
paste coupon code in your cart and click Apply after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGauto21, BG1111CAR, BgAuMotor, BGAutos, BG7705, BG8109, BGSP63, BGCARELEC, BGCARPRO, BGBT2910, BGBT2911, BGAFF10OFF, d50480, BGCuponation10, BGHONEY2110, BGBT292, BG10OFFAFF, BGwhielabel, 13f142, BG10OFFAFF1
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Price history (for all/most countries) for BT29 Car MP3 Bluetooth Player Charger is here. The lowest price was: $7.59.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).