Well, to be honest, if I had the premise of Monster Hunter described to myself 7 years ago, I'd probably not think that it sounds very fun either.
It doesn't matter if MH doesn't sound like your thing. The only way you'll know if you enjoy it for sure is if you try the game out yourself(either by buying/renting it yourself, or borrowing a copy from a friend. Not playing the demos because they suck for new players). It would certainly be worth your money since you can easily sink hundreds of hours into it if you give it a chance.
Hmm... Games that are cheap...
-Terraria has servers, but you'd need to set up your own one if want a private world to play with friends. It tends to go on sale pretty frequently.
-There's Hearthstone or the Pokemon TCG if you like card games, both of which are free.
-Pokemon Mystery Universe is a fan-made online game based off of mystery dungeon. Reborn has a guild there.
-Phantasy Star Online 2 is a free-2-play MMO, but it's in Japanese. You can look up a way to sign up, download and watch the game with an English translating around Reborn's Gaming General sub-forum if you're interested.
-Rock of Ages is a Monty Python-esque game which is where you and your opponent race boulders downhill to break down the enemy's front doors and squish them. During the time when your boulder is being constructed, you can lay down obstacles to slow down your opponent.
-Screencheat is an interesting shooter where you and your opponents are all invisible. How are you supposed to find your opponents? By screencheating. You can see your screen and all of your opponents screens regardless of whether you're playing local or online. May the biggest screencheating scumbag win!
-Awesomenauts is a casual, 2D MOBA. It's not free, but it costs about €10 last time I checked. Not sure if you'll be willing to give another MOBA a try, but the option exists if you want to consider it.