I agree build your own. So long as the usual precautions are taken and you are patient it will be well worth it. You must factor in the cost for the OS as well but its better than the ones tied into the premade systems. Fewer issues if it needs to be repaired, reinstalled or parts are changed. No garbage preinstalled to deal with. Make a list of a variety of parts that will do the job. If you get the parts over time the rebates and discounts can really add up. Dont worry about the latest and greatest for processors and video cards. The extra premium to get them isnt worth it. Sometimes a previous generation MB can be upgraded in the bios to use next-gen processors.
I imagine this is all SOP but make a partition on the second internal drive apart from just data storage that can be used as a secondary place to install programs that dont have to be on the C drive. Also programs that dont have to be installed at all and the speed of an SSD isnt required. Get all the needed first-install programs like anti-virus or downloaded graphic card drivers from the current system and put them on a DVD. After that image your C system partition. WD drives have a free application for this that will also work with other brands so long as the WB one is installed. Others might also.