I'm posting below the names of the Phones with approx prices which lie in B/W the PKR. 15,000 to PKR. 25,001 range which might help you even further:
BlackBerry
Pearl 8120
Rs. 25,000
Sony Ericsson
P1i
Rs. 24,350
Sony Ericsson
M600i
Rs. 23,300
Motorola
RAZR2 V9
Rs. 23,000
Nokia
N76
Rs. 22,700
LG
KF600
Rs. 22,500
Samsung
F400
Rs. 22,500
Nokia
N73 Music Edition
Rs. 22,300
Motorola
RAZR2 V8
Rs. 22,300
Nokia
6500 Slide
Rs. 22,300
Nokia
E65
Rs. 21,600
Nokia
N80
Rs. 21,400
Sony Ericsson
W910i
Rs. 21,400
Nokia
E61
Rs. 21,200
Sony Ericsson
W950i
Rs. 21,200
Motorola
RIZR Z8
Rs. 21,000
HTC
P3400
Rs. 20,500
Nokia
N91
Rs. 20,400
Sony Ericsson
P990i
Rs. 20,200
Nokia
5610
Rs. 20,100
Sony Ericsson
W850i
Rs. 19,700
Sony Ericsson
T650i
Rs. 19,350
Sony Ericsson
W880i
Rs. 19,300
Nokia
7900 Prism
Rs. 19,200
Samsung
D880 Duos
Rs. 19,200
Motorola
Moto Q
Rs. 19,000
imate
JAMA
Rs. 19,000
Nokia
E51
Rs. 18,900
Nokia
N73
Rs. 18,600
LG
KF510
Rs. 18,500
Samsung
i450
Rs. 18,300
O2
XDA Stealth
Rs. 18,000
BlackBerry
8700g
Rs. 18,000
Nokia
6500 Classic
Rs. 17,900
Samsung
D780
Rs. 17,900
Nokia
5700
Rs. 17,100
Samsung
U700
Rs. 16,800
Sony Ericsson
K810i
Rs. 16,750
Samsung
F300
Rs. 16,300
Motorola
A1200
Rs. 16,200
imate
SP5m
Rs. 16,100
Nokia
5500
Rs. 16,000
Nokia
7370
Rs. 15,700
Nokia
5310
Rs. 15,700
Nokia
3250
Rs. 15,600
Sony Ericsson
K660i
Rs. 15,450
Nokia
6270
Rs. 15,400
Samsung
E900
Rs. 15,400
Nokia
6120
Rs. 15,300
Sony Ericsson
W580i
Rs. 15,250
Sony Ericsson
Z610i
Rs. 15,100
P.s. the price may not be accurate but are just there to give a rough idea of what the actual price may be.