When hay is in short supply or non-existent, what do you all feed? What's most cost-effective & best for long-term feeding? 

I would go to cubes first, then pellets

I've fed soaked beet pulp and cubes as a hay supplement. Luckily, in my area this year, we have hay.

We normally have plenty of hay.  The rain this year has caused so many issues.  I feed alot of US Alfalfa (dehydrated alfalfa) when I'm low on hay.

Alfalfa cubes and beet pulp soaked