I can help you analyze the costs. So, the prebuilt costs about $220 more.
If you added an SSD to the parts list I recommended before, it'd be be cheaper than that prebuilt PC. Think about it,
a good 240~256GB SSD costs about $80~90 but the prebuilt PC costs over $200 more.
For $150 you could get a decent 500GB SSD.
As for the graphics card.. the GTX 980 typically isn't recommended around here. Not because of it's a bad graphics card, but because the performance it offers is not really worth the cost. The
GTX 980 costs around ~$430 at the cheapest and the
GTX 970 costs around $300 at the cheapest, but the GTX 980 only outperforms the GTX 970 by roughly 10~15% according to
TechPowerUp and
Anandtech. Yeah, paying over 30% more money (from $300 to $430) for a 15% performance increase at best is not really something we'd recommend. If you're willing to read a bit and try some overclocking,
it's possible to make a GTX 970 match the performance of a stock GTX 980, making the GTX 980 even harder to recommend. Sure, the GTX 980 can also be overclocked, but it's still not that big a difference to warrant the extra $130.
Also, prebuilt "gaming" PCs tend to have questionable negatives that are common.
Look at this reddit thread, the person was contemplating buying the same PC, he contacted ABS (the company that assembles the prebuilt PC) and they were unable to tell him what model of power supply and motherboard was included in the PC because
they don't know. That's kind of silly. If it were a good power supply and motherboard, you'd think they would advertise that, but it's probably some cheaper parts that you can't be sure about the quality. The power supply is important because it powers everything in your PC, you need higher wattage for overclocking and any future upgrades you'll be doing, and a bad power supply could ruin other components if it dies. The motherboard is important because it determines what it's compatible with and how well it can handle overclocking the processor. If it's a cheap motherboard, then it's kinda doubtful if it'll be totally stable when overclocked, or may not allow very high overclocking.