I build them for myself and friends. Good cores are tougher to come buy now for big blocks. Lots are choosing to either build a stroker small block or switch to a 3G hemi. If you have a decent core and are building a mildly hopped up street engine it is not hard to build one yourself. Despite what some will tell you, it isn't necessary to spend $1500 on just block machine work to build a nice running street engine and have fun with it. Yes, factory tolerances can be improved upon, but lots of engines ran a lot of miles with factory parts for decades.