Prices are locked until the game starts so you are good on that front. Only way you can profit by making a squad early is to target a player that will make a move to the team that you want to have a lot of players from. Let's say in your case you already have 3 LFC players and you hear Palmer is coming to red side. You take him before the transfer is official and you have 4 Liverpool players until the moment you transfer one of them out.

I will only accept side bet from those who finished below me last season..