In reply to Pink Marshmallow:
I have this problem as my feet are a miniscule 2.5.
If you are absolutely sure that the 4.5 is what you want, most shops will order them for you in that size. Be warned, however, that they will often not accept a return unless it's a manufacturing defect because they struggle to sell them on. I have had both Cotswold and Tiso do this for me (although I often have to take my old shoes along to prove that 5.10 actually do make anasazis in size 2!).
If you want to try them on first, you might have more trouble. I have best luck at shops attached to walls as they tend to have more kids through the door, but it sounds like you have already tried that.
I often find they take a couple of weeks to arrive as they are often special ordered from the US. Also, with the very small sizes, they do small production runs and if there are none left you have to wait for the next batch. This might not be such a problem at your size though.