Here are some components to consider (prices are in Canadian dollars from NCIX):
$110 Gigabyte Z77M-D3H micro-ATX LGA1155 motherboard
or $155 -20MIR Asus P8Z77-V LK ATX LGA1155 motherboard
or $ 73 Gigabyte B75M-D3H micro-ATX LGA1155 motherboard
$ 99 Intel Pentium G850 Sandy Bridge 2.9 GHz dual-core LGA1155 processor w/ HSF
or $142½ Intel Core i3-2120 Sandy Bridge 3.3 GHz hyper-threading dual-core LGA1155 processor w/ HSF
or $239 Intel Core i5-3570K Ivy Bridge 3.4 GHz quad-core LGA1155 processor w/ HSF
or $240 Intel Core i5-2500K Sandy Bridge 3.3 GHz quad-core LGA1155 processor w/ HSF
optional $ 35 CoolerMaster Hyper 212 Evo CPU cooler & fan
$44 2x4 GiB PC3-12800 Crucial BLS2KIT4G3D1609DS1S00 (DDR3-1600, CAS 9, 1.5 V) memory
$250 MSI Radeon HD7850 2GB
or $239 Sapphire Radeon HD6950 2GB
or $240 -30MIR Zotac GeForce GTX560Ti 1GB
or $224 -20MIR MSI GeForce GTX560Ti 1GB
or $135 -20MIR Gigabyte Radeon HD7770 1GB
$ 85 120 GB Corsair Force GT (SF-2281) SSD
$ 85 1TB Seagate ST31000524AS (7200 rpm) hard-drive
$ 20 Asus DRW-24B1ST DVD-RW
or $ 89 Asus BW-12B1ST Blu-ray burner
$ 13 Flash memory card reader w/ USB3
$ 55 -15MIR Antec Three Hundred ATX case
or $ 70 Antec Three Hundred Two ATX case
$ 50 Antec EarthWatts Green EA-430 (32 A @ +12 V) power supply
or $ 64 -20MIR PP&C Silencer Mk III 400 (30 A @ +12 V) power supply
or $110 Antec Sonata III ATX case & EarthWatts EA-500 power supply
$120 Microsoft Windows 7 Home Premium 64-bit OEM
$198 LG IPS231P 23" 1920x1080 e-IPS LCD monitor
or $138 HP LV2311 23" 1920x1080 TN LCD monitor
$ 10 -5MIR Zalman 5-button mouse
$ 15 Microsoft keyboard 600
$ 40 2.1-channel speaker system