Does anyone think it's possible to combine two base games together for a bigger game?

Not really. While you can play the military and conquest game over a vaster playing field, your quest game will be heavily changed by adding two of the same tile. Also how would you differentiate between your knights and another player's? Also how would you set victory conditions with runes?

What exactly are you trying to achieve? Do you just want to play with more players? Are you trying to make a giant map? Are you trying to have larger battles?

I was trying for a bigger map but a little bit of everything sounded great

You can find some extra factions on BGG, Orcs and Dwarves should really be a thing anyway in the setting. That can get you up to 6 players that way (I'm actually working on an orc faction atm).

If you just want a larger map, give each player 3 cards instead of 2 for building a map (there are 12 with the expansion)

How in the world do I get the expansion without spending a fortune I wish I was into this game back when it first came out.

I wish I had a good answer for you, as it's one of my favorite games too, and the expansion is quite worth getting.

I can only hope that I'm right and that it will be rereleased as a second edition soon.

I can't believe it, but I found it today they had a copy of the expansion sitting at my local store. They said they've had it there since it came out but no one had bought it. I'm super excited!! Thanks for the help hopefully this is what I was looking for.

It adds new areas, quests, heroes, units, and great optional rules. It's well worth owning.