Well, if you say new heads are $700, I searched autozone and all together the valves, springs and spring locks only come to $262.
Exhaust valve $8.00 x 8= $64
Intake valve $8.00 x 8-$64
Spring lock retainers $32
Of course you will have to resurface the valve seats and will need a valve spring compressor. Plus, if you are going to replace the valve guides that will be a little more. I would shop around some more. Maybe www.jegs.com, www.rockauto.com ,etc.