SUT for AT-OC9XSL?

I have a Bellari in my collection of SUT's. Excellent for around $320!

Rothwell should have one and he uses Lundahl transformers. You might even be able to find one on the pre-owned market at your budget. New might be a little higher but not way out of budget.

You are leaving an important parameter out of the equation. What is the gain of your phono stage? What is the output of your cartridge? If you can make do with a baseline step up transformer that has a one to 10 gain ratio, then there are a myriad of choices that work with your cartridge. A 1:10 SUT into the typical 47K ohm input impedance of an MM phono stage will result in your cartridge seeing a 470 ohm impedance, which is excellent . Your cartridge will even be ok with a 1:20 SUT, but only if the gain parameters suggest you need it. Perhaps you’re confusing the use of a SUT with issues related to using a “trans impedance” phono. That’s a whole different can of worms. With certain transimpedance stages, the 12 ohm internal resistance of your cartridge might not be optimal.