A good alternative to the cubes if you are stuck without the real deal is Better than Bullion.
Not cheap, but convenience never is.
Still pretty salty, tho.
Another alternative is a low sodium CARTON of stock.
Resealable and will keep for a while if kept cold (take from fridge, pour and stick back in fridge).
Get in the habit of keeping a few containers in your freezer, to keep trimmings for stock, well marked with start date and contents.
One for beef bones and trimmings, one for poultry, one for veg.
Be aware of the condition and quality of what you freeze...bad ingredients make bad stock.
I also do not "season" my stock.
Way more versatile to save the herbs, S&P for actual dish.
Pick a day when you are gonna be home all day and make your own, portion out to muffin pans and freeze.
Place these little chunks of goodness in another well marked container, place back in freezer.
Well worth the effort and very simple.
mimi
*OBTW...welcome to CT!