Step-down transformers to household use

Hello all you folks who have moved here from North America, where the household AC current is 110 Volt. If you have had to purchase a step-down transformer to power your imported electrical equipment here in Oman, could you please share where in Muscat you have found one? I brought a couple of these with me but, as it turns out, it is not enough! Thank You.

Builders' supply shops have them as sites use 110 through isolation transformers for safety.
The things are big and yellow but will work a treat for pretty much anything you are likely to use at home.

Thank you very much,  I will check them out!