Is he good with cheese?
You could, instead, go with:
Human (love the bonus feat and extra skill pts), 2 flaws, and the trait Quick (giving you -1 hps per level, but +10ft to your base speed, must have a Con of at least 4)
Warlock 2/Beholder Mage 1/Warlock +2/Eldritch Theurge 7/Hellfire Warlock 3/Eldritch Theurge +3/Warlock +2
Gets you a Warlock of 19, an arcane caster of 20 (not sure how the 10th level of Eldritch Theurge would affect the Beholder Mage class which caps at 10th level) with 9th level spells that you can learn as a Wizard, cast as a Sorcerer, and cast one spell of EACH level from 0-9 as a free action EACH round.
All you would need is an Int of at least 17, and spend 890 gp of your 900 gp at level 2 to get Enlarged and then Polymorph Any Object-ed into a Beholder. Using your two flaws, pick up Assume Supernatural Ability: Anti-Magic Cone and Assume Supernatural Ability: Eye Rays (can easily be said that some where, back in your ancestry, someone had relations with a Beholder which lead to some minor affinity to its supernatural abilities in your family hundreds of years later). So your third level you can put out your central eye, take Beholder Mage, and, since it is the first arcane caster level you just got, take Precocious Apprentice as your 3rd level feat.
By having the same Int (17), the same size (large), and the same kingdom (animal), you get a 9 for the Polymorph Any Object spell, making it permanent. Naturally, it is a transmutation effect on you cast by an 11th level caster, so it could be dispelled, BUT if you make it to Eldritch Theurge 7 (i.e.: level 12), you can gain Polymorph Any Object yourself and cast it over and over on yourself for multiple layers as a caster level of 16 (since your caster level is 2x your Beholder Mage effective level).
The main reason for this is so that you can do the following: at level 12, you can take Extra Spell for your feat, and you can gain the Wu-Jen level 7 spell Body Outside of Body, since you'll be able to cast 8th level spells from the Beholder Mage PrC advancement.
This will allow you to create 3 duplicates of yourself (granted without spell casting ability), but they last for 1 minute...AND RETAIN ALL OF YOUR WARLOCK ABILITIES!!!
So you and your 3 duplicate buddies can be a blasting force for 10 rounds during a combat, while you also get to wing out 0-8 level spells each round as free actions, all by level 12!
Of course, like I said, until your reach 12th level, you might get dispelled out of your beholder form. It would only be a 22 DC check on a dispel magic, but most casters who have it will need to roll at least a 12 at 10th level to get it to work. At which point, until the casters are dead, you could, in theory, ready an action to counter spell a dispel magic that will effect you since you yourself will be able to cast 6th level spells at level 10.
But, like I also said, this is cheese, and the DM might not like you for doing it.