That's really all you need. Argon so readily displaces atmosphere that setting up a purge is not difficult at all. In fact, You don't want any kind of airtight seal as it would negate the positive pressure that a little "leaking" will provide. Lots of times I will just use a spring clamp to attach the argon hose inside a tube and then just tape around the whole thing. Blue painters tape works very well as it leaves no residue behind. Of course, that is dependent on how close you are to the seam but aluminum foil works equally as well.
If you really are then this should be a no-brainer. If you really need to have some off the shelf products for your application and have plenty of cash, you might try a google search.