Made flush on flop... how much to bet?

[AtticusFinch]

Ok, feeling a little rusty after my break. This feels like it ought to be obvious, but I'll ask anyway.

$109 SNG, on BB with Jc4c, 25/50 blinds. 4 limpers, I check.

Flop comes 6c7c9c.

I come out betting 125 (half the pot). Folded to the button, who pushes in his 875 remaining chips. I call and villain turns over 10c2c.

I'm curious mostly about my flop bet. Did I leave some money on the table here? Alternatively, is my bet too small considering how many players are in? After all, I don't want AcX getting odds to take off a card because of an in-between caller. Comments?