Are you able to go to a tack store near you, and have a trial run with the tack for a few days/day? If so, you could probably find a saddle that fits well on your horse, and search for more saddles of that type. There are 4 arabs at my barn, and they all use regular tack. And what I mean by that is, they don't use the 'arabian saddles' ect.
I have been able to use normal tack on arabs and arab crosses. What are you looking for? Saddle, bridles, halters, bits? If you have to order from somewhere, often if they don't have an actual 'arab' size, the small cob sizes work well for Arabs. Halter wise, if she has a really petite head, normal sized yearling halters fit well. If you can't find something specifically for Arabs you can always 'improvise' using other sized ones. Western bridles I've never had an issue fitting to a smaller head, because alot of them are designed to go smaller.