It is very possible that tickets are sold out. Here in Phoenix we do not have laws against scalping and what happens is "outlets" buy tickets, mark them up and then sell them online to visitors. As spring training gets closer it isn't unusual to see tickets going for $70-200 above face value. Most of the clubs here don't start selling until next weekend.
We are going to the game the Braves play against the Dodgers. My best friend's husband works for Dodgers so getting tickets isn't an issue for us, fortunately we have never worried about it -- just tell his asst. when we are going and it is all arranged for us. I do know that last year the Braves stadium looked full for the game we went to see -- it was their second game, against the Dodgers. Perhaps that game will not be quite as busy -- that is the one we are going to this year. I'm not sure if there is any excitement around the Dodgers there -- baseball isn't really anything I follow, except for the Dodgers ... so I am not much help. Sorry!
There are a couple other things though, I just thought about ... you might check back as it gets closer to the game. Sometimes the visiting team will release tickets that can be sold. Also, at least in Phoenix, there are typically people selling tickets outside the stadium. There may be laws against this in Florida --not sure. And, we often find people selling spring training tickets in the local newspaper and on e-bay. They are still a bit more than the face value but often not as high as the online distributors.