[Build Help] Need help building a computer for 150-200 USD

At our family business we have some really old computers, like Windows 98 old, and we would like to upgrade them. We've looked on E-Bay for computers but nothing really fits our needs. The computers are used for basic software programs like Microsoft Office and we don't need much hard drive space. We also do not need a monitor, keyboard or mouse. We are looking to spend about 150-200 USD for each computer. Is it possible to build a computer for this cheap? And Windows 7 is preferred (64-bit or 32-bit) Thanks for the help!

EDIT: Since it seems to be impossible to build a PC in this price range. Can anybody supply me with some links of used/refurbished computers that would work?