OK, now you go look at how Belly always signs quality DT's for cheap. He doesn't have to pay for them and knows it, especially since he can make guys who are average or have been underachievers and get them to play at a higher level. Does it ever year. The latest is Lawrence Guy who was unnoteworthy at best coming in, but now is a top tier run stuffer.
Spending money and high draft picks on a position does not mean you don't value the other positions. Belly's emphasis in FA is on the DLine. Carl Davis is currently on the roster, another underachiever who he will get to play well, most likely.