Does anyone know what a show quality Mille Fleur looks like?

Hard to tell at that age. The older they get the better they are. Here are a picture of mine just under a year old.

These are a great breed for showing.  We got ours from Cackle as well and started showing in some of the local shows last year.  We have been showing our little roo Simon.  He has placed in every event so far.  We are thinking of moving up to maybe some of the county or state fair this fall.
There are a number of clubs and organizations that can be a big help.
I suggest looking up the Standard of Perfection and picking your best birds and starting with some small shows.  That way you have a good chance at a ribbon and can talk with the judges on your birds strong and weak points.
I would say keep them.  They're small, don't eat much and can be a lot of fun.
Here are some of ours.

Here's a link to the Standard of Perfection, it's from the Belgian Bearded d'uccle and Booted Bantam Club.  http://belgianduccle.hypermart.net/dUccle1page.html

This is my boy, Sebastian. I think we got a lucky gene mix in a chick from our local Tractor Supply Co.

If you got that from the TSC you are very lucky. That is a great bird right there. Color is right on.

Thanks!

Check out the d'uccle thread.  There are some nice looking d'uccle pics on there in all colors including Mille Fleur.  'Tennessee' looks pretty good (Wegotchickens)  and I also think the mille fleur rooster on the MyPetChicken website is gorgeous.

The main thing is you want nice fluffy cheeks-- muffs-- and a fluffy beard too, plus vulture hocks and feathered feet with feathers on the middle toe.  It helps if they have the five points on the comb, and they have tiny wattles- almost nonexistent.  They also don't like a really long body or long skinny neck.

One of the pictures above is of a booted bantam mille fleur, it has the color and the feathered feet, but no beard, and good sized wattles.