As others have mentioned:
David Winston
Charles May
Ken Honeycutt
Those 3 and Mr. Ingram have a lot of similarities in their knives. Each have their own distinct patterns and look/feel, for blade profiles to grips to sheaths. I think there are a lot of good makers whose quality of production will be on par with Mr. Ingram's, but if looking for a knife "like" an Ingram I think the three listed above will be the closest.
This.
Lots of makers doing work was good as Gene but the above mentioned will be the most similar to an Ingram
