Saltwater tank setup?

Ok, I need some help with a 90 gal. saltwater setup, I need to know what to buy for it, it is being built into a support pillar in my living room, you will be able to walk all the way around it. the short sides will have drywall over them. so my problem is that the short sides which are 18" wide are the only place that I can put all filtration. I plan to have live rock and fish maybe a star fish once I figure it all out. money is not a problem within reason I would like to stay under $1000 if possible. also how much sand should I put in the bottom? I had guessed around 75 lbs. is that about right?