The lowest price civ 5 complete goes for is around $12 up to $16 depending on the sale. I would recommend using http://isthereanydeal.com/
You can check prices of a single game on several sites at once.
EDIT: turns out it's on sale right now (~~mac only?~~Steam code!)! http://www.macgamestore.com/product/3172/Civilization-V-The-Complete-Edition/
I found the complete edition on Amazon for less than 20 (there are other more expensive copies on Amazon as well). Looks like it's going through a third party but it's "Fulfilled by Amazon" whatever that means. Maybe research the 3rd party people? Looks like they're actually selling a disk-based copy.
https://www.amazon.com/Sid-Meiers-Civilization-V-Complete-PC/dp/B00HWMP0TU
Science is the most important attribute, along with population. With science you can create a more powerful military, create a more powerful economy by getting more economic buildings and trade routes, with science you can create a better culture by getting access to wonders, normal culture buildings and archaeologists faster, with science you can improve your production and population, and even your faith!
Science is king, if you let it sit on the back burner you better have a good reason. The best reason I can think of is war. ". . .war is of vital importance to the State. It is a matter of life and death, a road either to safety or to ruin. Hence it is a subject of inquiry which can on no account be neglected." ~Sun Tzu, The Art of War
yeah but it's a bit of a pain:
Hi, the game will run on your laptop without problem. The performance of the game depends more of you specific game setup like how many AI Civs you play with or how big the map ist.
Wait for a steam sale and buy the complete edition. It contains all Addons and has a quite different gameplay than the vanilla version. It was already available for under $10 at steam. You can also check isthereanydeal.com/ or another site which compares the prices.
You can get it quite a bit cheaper through some other sites, such as http://www.cjs-cdkeys.com/products/Sid-Meier%27s-Civilization-V%3A-Complete-Edition-CD-Key-For-Steam.html. The I would say that it is DEFINITELY worth it.
You can download it from here: https://visualstudio.microsoft.com/vs/older-downloads/isolated-shell/
Just tick the box to agree with the licence agreement, and choose the appropriate language, probably the en-US one.