Lots of good advice here, but I'll just chime too. If money is no object then I would say the best bet is to pledge Raise the Dead ($210 + $45 Shipping) to get all 3 sets (Season 1 & 2, plus TCM expansion), as you planned, then purchase every optional survivor, Dakota, Fred, Lea, and Rick, and Adriana ($10 each, or $50 total). This will give you the full experience.
Now, as Bailey03 mentioned, if you want to create your own scenario's then buying an extra set of TCM tiles is a good idea, because this way you can play both sides of every tile, 4 one side, 4 the other to create a larger mall. I've been considering doing the same, but I'm more likely to go with the scenarios created by GG or other players, and those only use the base tile sets so you don't need/use extra tiles to play them.
I seriously doubt you'll need to buy more dog companions, as the stretch goal already gives us 6 dogs (2 of each type) for free. That's a lot of dogs, and considering the melee bonus they grant survivors, you may not want a player getting 4 bulldogs... I'm just sayin'.
As for the BoZs... that's up to you. They'll use the new models (introduced in the Kickstarter) and come with new zombie spawn cards. For me, I run games using my Season 1 box set which came with 1/3 more zombie miniatures and I have run out during some crazy ones that reach Red Level. The rules state zombies you cannot place all get an extra action... so if you don't want that (more than 50% of "failed" games I played in were caused by zombies getting extra actions) then getting more zombie miniatures would reduce this possibility. Your call, your money.