I called Edcor once about custom winding some power transformers. They will do it but at a price. Once you order it they add it to their catalog for the next guy at the normal price. At least that's my understanding.
Last time I checked (several years ago) Heyboer will wind custom spec'd stuff for minimum additional charge. My experience is have them do it on their automated winding machinery with their best steel core material, even though you need to wait for corporate orders to complete so the machinery is freed up. You will get a more consistent result that way. Several pieces they hand wound for me had poor regulation properties (voltage sagged substantially under full load as opposed to no load). They redid those for me for no charge but still it took an extra few weeks of back and forth and it would have been just as easy to wait for the winding machinery to free up.
Last time I checked (several years ago) Heyboer will wind custom spec'd stuff for minimum additional charge. My experience is have them do it on their automated winding machinery with their best steel core material, even though you need to wait for corporate orders to complete so the machinery is freed up. You will get a more consistent result that way. Several pieces they hand wound for me had poor regulation properties (voltage sagged substantially under full load as opposed to no load). They redid those for me for no charge but still it took an extra few weeks of back and forth and it would have been just as easy to wait for the winding machinery to free up.