Have no experience with National or Ramline. Ramline has been in business several decades and have not heard anything derogatory about them that could be verified.Ruger 10/22 plastic magazines are how they seem to have gotten their start.National is an after market magazine and it may be a good idea to stay away from after market magazines. The one exception is if the mags are used for practice only and marked in some way as such.
www.ajaxgrips.com and J&G Sales are known as magazine suppliers as well. If not, then check with
www.brownells.com or
www.e-gunparts.com . Might have to be patient and let these mags get into the supply pipeline. Demand can be greater than supply for gun parts or equipment. Ammo can be the same way. I have Mecs for my Ruger pistols and have had very good service from them.