What's a good step-up transformer?

Try a Cotter; many say it is one of the best available. First choice would be a classic Kondo Audio Note tranformer but, as you said, they are not cheap. My recollection is Bryston also sold one that was simply a rebadged Cotter.

Ortofon still makes two transformer models, also (or maybe it is Dynavector). One is reasonably priced and the other is a couple of grand and goes the full silver wire route.

I have seen a couple of Cotters for sale and they are around a grand. You can buy a new Audio Note for less than a grand (not silver, of course). There is a Kondo S9 Transformer on Audiogon now at 1700/bo; if you can afford it you could probably pick it up for a price that would allow you to use it and then sell it for not much less than what you paid for it as the major depreciation has taken place at the prior owner's expense.

EAR also makes a nice transformer you can buy new but it somewhere between 500 and a grand is my recollection.

There is an Audio Innovations transformer for 200/offer. That is the company where Peter Qvortrup worked at prior to doing the Audio Note UK business. Might be worth checking into.

Check out Jensen...it makes high quality transformers, too