I picked up an old Motobecane conversion that still used the original QR for the front hub. I'd like to swap for a solid axle. I've not done this before and it seems pretty straight forward. Is there anything special I need know?

Perhaps the bigger question is, where is the best/preferred place to buy a new axle? LBS? Online? It doesn't appear to be a common part. I'm assuming width matters here, but I should be able to figure that out based on the fork I've got.

Thanks!