Well yes, and you never will. But if you have enough favour with both, you can offer your reputation as a fulcrum that lets the two economies interact.
There's probably going to be fucked up exchange rate, there is no way someone like Kragg or even just a normal conservative runelord would ever buy a trinket from a wizard (or sell one to them) but there may be a way forward. Won't know until you try.
There are plenty of opportunities for stuff that's useful for a karak that wizards can produce that runesmiths can't (or can't do economically). For example, charging up a Rune by use of eight mono-wind journeymen (AV exists, but in rare supply, certainly less than the demand for it)--and the only other way to charge them up without AV is to go to a Storm of Magic, which is difficult, dangerous, time-consuming, and unpredictable.
Hell, Belegar paid a lot to get the Colleges to help made the Eye of Gazul, and it's the shining jewel in the crown of Runesmith-College synergy.
You'd only have to pitch it as combining the strengths of both without combining their limitations, and consider the possibilities.
Seed of Regrowth must not pass into hands of enemy. Putting it on a journeyman that will possibly wander the breadth of the world seems like an error of judgement.
We got the Seed of Regrowth as a brand new magister, off to go adventuring in the Badlands. Into a place infested with several clans of skaven. We put the Seed at more risk going up against Alkharad and those Chaos-worshipping Norscans than Eike is likely to find journeying. After all, it's not just an item that you can use easily, you have to know the specific mneumonics (and that it even uses mneumonics) to activate a charge, to recharge from another being or corpse, and how to transplant it into yourself.
Eike is already approaching the level of fighter that Mathilde was as a Journeywoman, and we should be able to get her the rest of the way there before she goes on her journey.
More than that, the Colleges
already have a policy that it's good to give journeymen a leg up so that they're more likely to survive their journeys, what with the Bright College handing out enchanted rings made by
Teclis to new journeymen for that very purpose.
Had Mathilde had the Seed as a journeywoman, she wouldn't have almost died at Drakenhof and she could have saved Abelhelm with ease.