I have many subcontractors complaining that they are frustrated with the tendering process because main contractors use it to screw down prices.
While price is always an important element, in many cases a subcontractor (who is an expert in his field) can help you win the main contract by sharing their skill with you. I've been in a situation where a subcontractor shared with me a different (and superior) way of installing curbing on an athletic track that we then recommended and it helped us to win the tender.
A win-win situation like that will always turn out better than a win-lose one.
