get one of your mates to help you you could spend the cash on a better LGA1155 mobo and CPU.
Initially I got an Asus P8P67 and a Intel i5 and a reasonable ASUS EAH5770 Graph card (1GB GDDDR5). I paid about $600 Australian for all that with 8Gb of ram, a new CD/DVD Drive, HDD and a power supply. I used an old case that I had lying around.
Find the cheapest enthusiast computer shop near you or do your research and buy the bits online.
I use Ebay in the USA to buy high end CPU's and ram. I have found that its better to buy the motherboard where I live due to high failure rates in the past with DOA motherboards bought in stores. (Its easier and quicker to negotiate a return with a store than online.)
Later on I upgraded to the Intel i7 2600K and bought a Corsair H70 cooler unit with a view to overclocking the CPU later.
To mount the Corsair water cooled fan I had to carefully measure and cut a hole in the top of my case to mount the 120mm radiator fan between my power supply and CD-DVD drive.
If you built the computer yourself, or get a mate to help, you can spec it how you want and upgrade it later on as you can afford it.
Those prefabricated boxes like your looking at usually have lower spec motherboards, graph cards, ram and slower CPU's than what is ideal for gaming, or other high end graphical applications such as video editing or photoshop. (they are also about twice the price of putting one together yourself).
Just make sure when you buy the motherboard it is compatible with the most overclockable CPU in single core applications for running MAME.
At the moment the Intel 3.4ghz i7 2600K is king, able to run stable at 5.1ghz overclocked in single threaded applications (MAME).
If you cant afford that CPU, around $250-350 off eBay, then start with an LGA 1155 i5 on an LGA 1155 mobo and upgrade later to an i7 2600K when you can afford it.
I use and recommend ASUS motherboards.