This power supply: https://www.amazon.com/gp/product/B00H33SDR4/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1I would suggest getting a psu that has the correct amount to connectors. But depending on what exact power supply you have, it may be possible to use the molex to 6pin adapter.
Any power supply of some quality will include more than enough PCI-E cables.My power supply is the Thermaltake SP-650P. Non-modular, cheap (about $50), and it still has 6+2 PCIE cables.