That dealer would be Harry Taylor's, and he runs an excellent forum on Omega enlargers as well at the site.

You can find lensboards, lens cones, and good lenses cheaply on eBay, as well as Omega negative carriers (I like the Rapid Shift carriers) and all manner of obscure Omega parts. I really went to town with this stuff and accumulated a stack of negative carriers for every format I shoot, a tilting negative stage, 4x5" copy attachment, reduction/copy bellows, all for a fraction of what it once cost.

Clean up the lens you have and see how it is. If it's not very good, try something like an 80mm Componon-S, EL-Nikkor, or Rodagon. All are modern 6-element lenses that can be had for around $50-75 on the used market.