When sourcing suppliers, we usually help our clients get a reasonable price and optimize for low risk, high R&D capability, or something of that nature. We are probably not the best fit for this situation.
If your main goal is sourcing products or components at the lowest possible price, Alibaba will probably be the best option.
Please Note: Buying cheaply from Alibaba usually doesn’t mean it’s the lowest cost in the long run, though, when ‘surprises’ such as quality issues, delays, etc. come up. They end up costing a lot more to the buyer.