I paid about 45 USD for my valve stem seals. In a SOHC it's not that bad, except on the back.

You don't have to remove the head. All you need is a compact style valve spring compressor, air compressor, a fitting to go into spark plug hole, MAGNET, vise-grips, a little oil, 10mm, 12mm, and 4hrs for a first time.

I think that should do it.