Just in case anyone interested. My own calculations.
Hopefully Anker Singapore give more
Shopee:
239.90 + free shipping + $6 off (store voucher) + $24 off ($6 off every $50) = $209.90
dont know whether can stack the ($6 off every $50) together with 18% cashback
with 18% cashback (cap at $6, payment by shopee pay) = $203.90
Lazada:
239.90 + free shipping + $15 off (store voucher) + $11 off (credit card discount min spend $200) = $213.90
with $18 off ($6 for every $60 spend) = $195.90
more savings if use with Shopback
Conclusion: Shopee is cheaper, but Lazada may be potentially even cheaper of can apply those additional discounts (to break $200) because u need to collect those discounts.