I have a 2005 Elantra with 22,000 miles. I have not replaced the air filter or the air conditioning filter. My questions are 1. Can I follow the manual and do it myself easily enough? 2. Should I by these filters at my local autostore or from hyundai?

Basically I want to know if other makes of filters are just as good or better than what Hyundai gives you.

 

Getting the air filters from an auto parts store is fine. The filter for the engine is very easy to replace... takes just a few minutes. I think all you have to do us undo the clips on the corner of the air box. If you have trouble moving it around, take the bolt out that holds the plastic heat shield to the top of the box.

The cabin air filter is pretty easy as well, but it takes a little more effort. Here's a good guide:
http://www.elantraxd.com/DIY/caf.php
You can either buy the part from Hyundai or get it from an auto parts store. Here's a hint: If they say they don't have a cabin air filter for an Elantra, ask for one for a 2003 Tiburon, either V6 or 4 cylinder, doesn't matter. They all have the same air conditioning unit.

When it comes to oil filters... I would recommend always getting the Hyundai filter and NEVER taking your car to a quickie oil change place that uses generic filters. Some people have even had problems with major brands such as Fram. The problem is that the Honda and Hyundai filters have the same base, but the Honda has a higher bypass pressure which means a filter made for a Honda will trash the engine in a Hyundai due to oil starvation. Purolator is a good aftermarket brand, but make sure it's the one for a Hyundai.