In theory, any "tender" is intended to identify the product with an optimal ratio quality-price. But, as the product requirements are usually formulated in very general terms, in practice the customer often has to choose between completely different products, with respectively different value. Figuratively - it is a choice between "small for three" and "large for five", where the quality of both products is the same. If we discard options "known results" and other tricks, the winner is the one who just guessing.
Therefore, in our opinion, there is a single acceptable way of tender: with a fixed budget.