Someone with a much larger mill should be able to face it for you either with a flycutter or large facemill, if they are good, they should be able to get at worst to 0.0005" out, or a machine shop should be able to regrind it perfectly flat.
Of course it depends if the table has been hardened, if it has, then grinding is the only way, but if it is a small 'hobby' type, then it should be fairly soft.
Find a 'one man band' jobbing type of shop, they are usually a lot cheaper than a production shop, as they are geared up to do one offs.
This is when having friends nearby can help.
Bogs