welcome to manhattan reefs.
that's a nice size tank, what are the dimensions?
as for stocking the tank do you have a preference for coral?
this will determine your equipment needs as well. an sps dominated
tank will need more light and a bigger skimmer as compared to a tank filled with just soft corals.
the cost is hard to say. let's say you want an sps tank, will you be happy growing your colonies from frags, or are you going to buy colonies right away? the cost difference would be huge.
these are some online stores I like, it will help give you an idea for cost.
for rock
ocean pro aquatics has an amazing selection.
for coral take a look at
http://www.reefermadness.us/, people on this site have been buying frags and colonies from them, they have some great stuff and they just became a sponsor of MR.
I looked at your cabinet plan, my one suggestion is too split the doors in two. the three large doors do not look balanced with the hardware on them.
if you used the touch latch hardware then you could get away with it. also those doors may start to sag on the hinges, they are longer than they are tall.