Here are the parts I've acquired over the last year. Almost everything was a special or sale. Just picked up the CPU from micro center for CHEAP, and got the SSD during an amazon price glitch earlier this year.
However, I cannot decide on a case. I want to keep it under $100 and relatively small, I won't be adding a ton of HDDs.
Those are my favorite MATX cases under 100 bucks. The air 240 has better airflow, but the Node 804 is quieter.
White variant air 240 (happens to be REALLY cheap at time of post): http://www.newegg.com/Product/Product.aspx?Item=N82E16811139045&cm_re=matx_cases-_-11-139-045-_-Product