$20 for Holliday is a good deal, IMO. He's coming off a bad year, but he's a solid hitter.
I would not have paid $8 for Trout, assuming this is a non-keeper league. He probably won't even break out of rookie eligibility this season.
Also, be careful about shelling out so much for so many starters. SP is deep, and there are plenty of good guys to be found for a buck or two at the end of your auction.
SecretAgentMan's strategy points are really good. Especially the first one, which is to understand that a player you put up for bidding does not need to be a player you want. Personally, I like to offer up "hot" guys I either don't want or know I'll be outbid on, so I can get that cash off the table. This year, it's guys like Darvish, Pineda, Strasburg, Hosmer, and Lawrie- they won't command elite-talent dollars, but they're unlikely to give the value they go for. Depending on how you feel about closers, offer up the elite guys early (Kimbrel, Papelbon, Rivera) and grab lower-end guys cheap.