yea thats really not a good plan, dont cheap out on a PSU, seriously dont. a good PSU is vital. i know there expensive and i know people dont like spending money on something that doesnt directly improve performance. but buy good buy once. PSU are usually the thing that dies on a PC and cheap one are normally the first to go.
what worse is cheap PSU have tendancy to take out other compoents when they die.
i reccomend a PSU from Hiper, PC power and cooling, Corsair, Akasa, coolermaster. not a random no named PSU.
also i would strongly recommend a Modular PSU.