Why are dualcore desktop PC's and Laptops very expensive in Nigeria? Especially online.

On the site below they sell stuffs @ a very cheap rate

http://www.tigerdirect.com/

1. Gateway
Intel centrino dual core2060, 1.6 Ghz
1024 mb RAM, 100gb hard drive
DVD/CD-RW Combo, wireless lan
15.4" monitor
N155,000

2. Compaq Presario C509NR
Intel (R) Celeron M CPU 440 1.86Ghz
Windows vista home basic
512mb, 80 gb of hd (5400rdm)
15.4", high definition brightview widescreen with intel graphics
media accelerator 950
Integrated highspeed wireless LAN
integrated altec lansing speakers
8x dvd_+rw/r and CD-RW combo drive with double layer
N140,000

3.Toshiba Satellite (3 of them)
Intel (R) Celeron M CPU 430, 1.6GHz
Windows XP home and windows vista capable
80gb of hard drive (5400rpm)
512 mb
14.1" widescreen monitor
DVD/CD - RW drive
Wireless LAN
WIFI certified
N135,000

4.Compaq Presario V6000T
Intel (R) Pentium (R) Dual core T2060, (1.6GHz/1MB L2)
Intel (R) Graphics Media Accelerator 950 with ports
Genuine windows vista home basic
512MB DDR2 system
Imprint finish + microphone + quickplay
DVD/CD-RW Combo drive
80GB 5400 RPM SATA Hard drive
15.4" WXGA Widescreen (1280x800)
802.11b/g WLAN
N140,000


5.Compaq Presario V6000T
Intel (R) Pentium(R) dual core T2060 (1.6GHz/1MB L2)
Intel (R) Graphics Media Accelerator 950 w/ports
Genuine Windows Vista Home basic edition
1.0GB DDR2 SDRAM
DVD/CD-RW Combo
80 GB 5400 RPM SATA Hard drive
15.4" WXGA widescreen (1280x800)
Intel(R) PRO/Wireless 3945ABG Network w/Bluetooth
N160,000

Call 08038686086 if you are interested. All laptops are american specs. They are all brand new.