There are no free-agent bargains -- at least, not at the time of signing, since, in theory, an efficient market with up to 30 buyers should price players appropriately, with the team that signs each player the one that had the highest projections for the player's future production.
That system will produce more bad deals for teams than good ones, which I think is a fair summary of the history of free agency in baseball. The bargains that exist tend to be ones we discover after the fact: the player who needed a change of scenery, finally got healthy, changed something about his swing or his delivery or his repertoire.