value on this river?

[oh boy]

villian is 78/0 tard that essentially never folds

PokerStars No-Limit Hold'em, $1.00 BB (4 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

BB ($115.65)
UTG ($98.50)
Hero ($212.85)
SB ($45.60)

Preflop: Hero is Button with K[img]/images/graemlins/diamond.gif[/img], A[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">1 fold</font>, <font color="#CC3333">Hero raises to $4</font>, <font color="#666666">1 fold</font>, BB calls $3.

Flop: ($8.50) 4[img]/images/graemlins/club.gif[/img], K[img]/images/graemlins/spade.gif[/img], 4[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">BB bets $1</font>, <font color="#CC3333">Hero raises to $8</font>, BB calls $7.

Turn: ($24.50) 6[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
BB checks, <font color="#CC3333">Hero bets $18</font>, BB calls $18.

River: ($60.50) 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
BB checks, Hero

bet if so how much?