Do you what i might have some good news to you.When you say white that there are 2 things that will case it,1st coolant leak into head but the smoke will disepate quickly ,2nd what i think it is,it is your transmission modulator is leaking and the vaccum from your engine is sucking it into the engine.So one quick way to check is take the air filter off and on the left rear close to the valve cover you have a vaccum line with a almost 45 Degree black bend vaccum hose.So remove that hose by pulling it off and check if it is wet at ALL.if it is wet than you have an easy fix.
The vaccum line itself is white and you might even see some red in it if the modulator leaks.An for doing the valve guide seals,no one should charge more than 4 hours for the job,what there hourely rate is up to them.Good luck Harald