https://pcpartpicker.com/ is good for exploring some new build combos. My prefered method for obtaining pc hardware is leveraging reviews from amazon and newegg for parts I can find on ebay.  Sometimes the stores are cheaper, but usually last gen parts are the best deal and are often in new condition.  There really should be some mention about making sure ram is compatable with the CPU and sometimes the motherboard may be picky about ram specs. 