What do you mean "full specced"? If you're wanting anything customized from the base options, you'll have to order it.
I'd say somewhere between 0 and 100%.
But seriously, like over analyzer said, generally the stores only carry the base models that are listed on the website. If you want to change any options to fully spec it out, then it's a build to order machine and you have to order it.
Although I have seen rare exceptions to this rule, I'd say your chances are small.
Apple generally always carries the base models and the top spec model. This is supposed to be the case with the Retina as well, but not likely until stock improves.
Top spec- as in the second tier base model, or the model I'm looking for?
I'm both working with my local Apple retail outlet, as well as have an "Ultimate" model on order at the online store.
So far, nobody's been able to get ahold of a model with the 768 GB SSD. (There's one person on the forum who was claiming they had one delivered from online store in the first few days after the announcement, but I think they were just BSing for feelings of self-importance.)
As far as what this week holds? Who knows. However, since not a single soul, even ordering in the first few minutes the store came back online, has seen the maxed-out SSD, I suspect they won't get to brick & mortar retail at least for another few weeks.
Just order online. If you read the stories on here, it can be a brutal attempt at futility to get the retina MBPs in store. If anything, you could continue the search in store, and then cancel the online order if you find the one your looking for.
If the chances are low, I'll just order it now so I don't have to wait longer
Thanks in advance!