In general as you get above $80 million the marginal cost of extra hitting seems to become much lower than the cost of fielding when normalized to estimated run impact. In other words, potentially in an OL cap and frequently at higher caps you'll get more bang for your buck paying for big bats with crap gloves than vice versa.
Note: By crap gloves, I sometimes mean crap but generally mean "average." None of those guys are poor defenders, and it seems that the cost of a decent glove vs. an awful glove is fairly low, so it's usually better to avoid guys who will pile up - plays and errors because, with a few exceptions, a similar bat with a glove that will lead to few + or - plays with fewer errors will cost a very similar amount. But an elite fielder costs a LOT more under the current pricing structure than an average fielder, even if his bat doesn't come close to stacking up.
Further note: That doesn't mean you can't build a successful $80-$100 or even $120 million team around elite fielders, and if you look around enough you'll certainly find some, but it's certainly not the easiest way to go.