I have a similar question, just like how the oz's do the cube can't you do a similar thing for making starter wort in advance? Without the need for a pressure cooker?

Basically my question is do I need to do the pressure cooker method if I keep the starter wort cold until I use it? So just make the starter wort and boil it and then go straight into canning jars and then into the fridge until I need to use them? Would this work or am I asking for trouble? I thought I read the bacteria will not grow below 50F if that's the case it should work?

I think that you're asking for trouble storing starter wort that has not been sterilized. Things do grow below 50F. To stop growth you would need to freeze to -80C.

Ive made a bunch of starter wort and put it into qt jars and "canned" them. I used my original ceramic pot for it. It felt strange to use my canning pot for actual canning!
It worked fine and dandy.

It's entirely possible that it would work the majority of the time, but a few sealed jars that do start to grow would make quite the mess...

I have been saving a quart of wort from each batch boil and storing them in sanitized mason jars in the fridge to make a starter a couple or 3 weeks later. So far I have had no problem with doing this. It's boiled before storage and boiled again right before use in starter. If this poses a real risk for health or batch quality, please advise.

Other than soured beer, the only concern would be "Botulism is a rare but serious illness caused by Clostridium botulinum bacteria. The bacteria may enter the body through wounds, or they may live in improperly canned or preserved food.", but don't know how possible this is in beer wort.

Well, if that's no greater likelyhood to occur under my conditions than setting my hair on fire from my gas burner, I may just keep on with what's been workin for me. Thanks for the info though. So I guess botulinum would not be killed off by the 2nd boil in any case?

I believe the bacteria would be, but if the toxin has already been produced, it would carry through. Not my field of expertise though.