hello i have a power book g4 whats the minimul cost of refurbishment for it?

Depends on what you want done, and as it is officially obsolete Apple won't do it for you. Try to find an Apple authorised repair centre who can give you a quote.

Depending on where you are, what country, etc, the choices of repair

and or restore services vary. Some of the better repair companies also

offer refurbished models with limited guaranty. Of those, you could ask

what an extended warranty over your repaired computer may cost, if

they offer such a thing for an extensive repair or restoration.

Cosmetic vs functional would undoubtably cost extra, since new case

parts and the like could be harder to get, as vintage went obsolete.

Some failed old models found their way into the used parts stream;

where in reputable situations, they get well-tested before re-use.

If you are shipping a computer, as portables are cost effective to

do so, you may find the range of quality & price more affordable.

Good luck & happy computing! 🙂

I see that Low End Mac has a facebook site that may offer you some assistance and advice.