Bant Company just had a stint as the best deck in Standard by a lot, and now Abzan Company is being considered the best deck in Modern. Collected Company has been all over competitive Magic, so this seems a good time to talk about the card's price.
The card's price has been rising steadily, if slowly, for some time. I advocated picking up a set for playing a while back in an Insider piece, though I didn't see it as being a great card to speculate on. After all, the growth has not truly been substantial. Had Collected Company never been printed in a preconstructed deck, it's likely that we'd be looking at a $30+ rare already. Given this printing though, the relative supply has done a good job of checking the admittedly high demand.
The sharp increase in Modern play and success might lead one to invest in Companies, though I would advise against it at this point in time. A very large number of this card is currently sitting in Standard decks, and while many players will be holding onto their sets for Modern play, there will be a dip as Standard only players move off of their copies. It happened to Wooded Foothills, so you'd better believe it will happen to Collected Company.
If you want to buy into the card to play any time before the card rotates out of Standard, you'll likely be spending somewhere in the $20-$25 range, though I expect at least a five dollar dip on rotation. At this point in time, I would recommend reevaluating the card's position in Modern and making a decision with regard to investing then.