I'm looking to pickup something new/used after Christmas that can handle games such as the Total War series, WoW and Civilization.

Would also be used for home use (music, surfing the web {MOTL}, Netflix, etc...).

No clue on a monitor either. I do already have an Apple cordless keyboard and an Apple cordless Mouse.

...and of course the cost for such a gaming PC.

But from what I recall, Total War will be your most taxing game, but all three will be more CPU heavy. That being said, the computer requirements to run these games aren't too extreme either.

Recommendations are based on knowledge of Haswell era parts.

Few questions:
(Assuming prebuilt)
1) Do you have any preference for any brand of computer?
2) Overclocking knowledge? Do you plan on overclocking?
If yes, I'd likely suggest an Intel Core i5-4690k.
If no, (even if it is a tad bit overkill) I'd look at the i7-4790.
3) How comfortable are you with poor quality graphics?
Most retail PCs come with mediocre (at best) graphics cards unless you're paying a premium. If you're comfortable buying a more powerful graphics card, and swapping it in in addition to buying a PC, this shouldn't be an issue.

Power supplies of retail PCs aren't known to be great, so you might have to replace this component as well.

If you're comfortable paying for your PC now, and waiting for your PC to be built through a boutique I could offer a few suggestions.

Digital Storm Online: I purchased a PC from them a looooooooong time ago, excellent customer service, amazing build quality. I've checked on them here and there throughout the years, and it seems their product choices have declined, and their prices have risen. Originally when I bought mine, it cost $100 extra (versus if I built myself) to have them build the entire system and ship it to me.

I have no experience from these boutiques, but only hear good things.
Falcon Northwest
Maingear PC
Origin PC

Avoid boutiques such as iBuyPower, and CyberPowerPC. Unless something has radically changed in the more recent years, they have **** poor customer service, and their build quality is terrible.

Another option is if you have a major Electronics chain like Frys or Microcenter, you can outright pick your parts, and they'll build your PC for you at the store for a small fee ($50, I believe)