Welcome to Mexico.

Mexico domestic fares are notoriously high..... there are few breaks other than the MexESAver fares on MX and the FareSavers on AM.

As you plan, know that generally MX flights are always to/from MEX, whereas AM does more flying amonth other destinations.

Aerolitoral and occasionally AeroMar give discounts for students, but you need a valid ID, etc., etc.

If you have SkyTeam miles, you might find them a good value for your intra-Mexico travel. Know that you can do Mexico-->Central/upper South America and back for 20k CO miles in coach with an open jaw and a stopover.