Per Unit Price
Supplier Rating + Reviews
The above things I look when sourcing suppliers. The most important thing is per unit price.
Lets take an example.
Lets say seller 1 have 5 star rating and pricing of $ 10 per unit. Seller 2 have 4 star rating and pricing of $7. Then I will give more preference to seller 4.
Response time is also an important factor. If the vendor have rating of 5 stars but dosent reply in time, I will not go with him/her.
So here it goes like
> per unit price > supplier rating > response time
When selecting a supplier I give more weight to reviews than ratings.