Queen makes a single blade version with D2 blade, bone or cocobolo handle, and Marbles made some recently (probably contracted from Queen) with a few different handle materials and 1095 blades, although they were on the expensive side.
If you look around ebay, you can find older ones that are in good shape and still don't cost a fortune. Older Ulster knives were high quality, and don't seem to command the high prices like Remington, New York Knife, or Case. You can get a good user in nice condition for around $40-50, the wood handled ones go for less. Another one to look for are Challenge Cutlery knives. And for really cheap users, there are plenty of older Imperials, you can pick up the cheap shell-handle versions for $5-10, so if you break or lose one it's not a big deal. Even the early solid-bolster bone-handled Imperials don't bring very high prices.