Do not, under any circumstances, pay for Fox Soccer Channel. Years ago it was great. Now it's absolutely worthless. They don't have a damn thing worth watching.
MLS is MLS. If you like the idea of watching local guys play and following a local team, do it. The product on the field isn't terrible by any means, but it does pale in comparison to what you'll see in the major leagues around the world. $80 is a good deal if you want to follow a specific team.
Your best option right now is to watch the EPL for free on NBC. They air one or two major games on the weekend, and you can access all the others on their website. They've made it damn easy to follow, and there's even nice league synopsis videos where they go team by team and explain their history and star players.
Regular ESPN airs major club matches for stuff like Champion's League, so you'll get your occasional exposure to Barcelona, Real Madrid, and Bayern Munich.
I watch every match of my favorite club in Argentina, River Plate, on the AFA website,
Futbol Para Todos, but I doubt that will appeal to most people.