I would suggest seeing if you can get tickets through their supporter group The Ruckus. Supporter groups are generally given a better rate for tickets, and sell at a lower rate. The supporter groups for any team can get very "un-disney" though, so if you are bringing young kids, the general sections are recommended.
Also, don't forget Orlando City SC is CURRENTLY a team, so there is no need to wait until they become a MLS team to see them play! ( unless 2015 is the next time you'll be in FL). They actually have several games scheduled at the ESPN Wide World of Sports this summer.