Add-on to what Rick said:

1. Jumpseating (for commuting) is free, in most cases, and I believe, unlimited.

2. ID90s and ZED tickets are standby. Your priority will generally be by seniority/date of hire at your carrier, but when travelling on other carriers---including jumpseat---it goes their guys first, then other carriers. I do not know what the pecking order is for other carriers, ie, do they go with their affiliated RJ first, then other majors, then all other RJs? I don't know.

3. ID90s and ZEDs are sometimes fairly pricey, and sitting in an airport for a couple of days, trying to get out, can be more pricey than just buying a ticket...especially if your travel is tied to something specific, such as a vacation and hotel/car reservation, and you now have to get a hotel in your departure airport, waiting for a flight that may never happen.