This one is self-centering, but again, DIY and I don't really trust myself to make it within tolerance.  Also it would be nice to just buy something (as long as it's not super expensive).  I don't get nearly enough shop time as it is. 

Don't fall into the trap that a decent jig is a one show pony.  You may not get much shoptime now, but you need to plan for the future... you will make other items albeit spaced appart and eventually you will retire and get more shoptime than you might wish for.
Just remember all the blogs you've read about people still using machines (whatever type/brand) made many years ago...  similar machines made nowdays are never that quality and machines made in the future might not be the quality of those made today. 

If your first cut is too short... Take the second cut from the longer end... LBD