$6.50, semi-bluff with 3 others in the pot?

[JuntMonkey]

Do you bet out here 4-handed, or only with 2-3?

PokerStars Tournament, Big Blind is t30 (7 handed) Converter on pregopoker.com

UTG (t1390)
UTG+1 (t1470)
MP1 (t1960)
CO (t4620)
Button (t1160)
Hero (t1450)
BB (t1450)

Preflop: Hero is in SB with 8[img]/images/graemlins/club.gif[/img] 9[img]/images/graemlins/club.gif[/img]
<font color="gray">UTG folds</font>, <font color="gray">UTG+1 folds</font>, <font color="gray">MP1 folds</font>, CO calls t30, Button calls t30, Hero calls t15, BB checks

Flop: (t120) 7[img]/images/graemlins/club.gif[/img] 8[img]/images/graemlins/heart.gif[/img] Q[img]/images/graemlins/club.gif[/img] (4 players)
<font color="red">Hero bets t90</font>, <font color="gray">BB folds</font>, CO calls t90, <font color="gray">Button folds</font>

Turn: (t300) J[img]/images/graemlins/heart.gif[/img] (2 players)
Hero checks, CO checks

River: (t300) A[img]/images/graemlins/spade.gif[/img] (2 players)
Hero checks, CO checks