All of the equipment you can buy varies in price significantly based on size, quality, name brand, new/used, etc. You could easily get the same stuff for under $500 or spend north of $3000.
For a 3-tier set-up you need the minimum (and I'm likely forgetting some things):
Equipment:
Space to store and use the equipment
Heat source(s) -- my 3 vessel system had 2 burners
Hot lauter tun
Mash tun
Boil kettle
Chiller
Fermenter
Serving vessels (kegs or bottles)
Accessories:
Hydrometer
Thermometer
Fittings
Hoses (not actually required, but very useful)
Cleaning and sanitizing chemicals
Spoon/mash paddle/huge whisk
Bottle capper
Kegs
Valves
O-rings
Brewing salts for water treatment
Table/cart to put things on during the brew day
Options:
Sparge arm
Pump(s)
RIMS or HERMS
Kegerator & all associated accessories
Grain mill
Tools needed:
Drill
Step bit
Screwdriver(s)
Nearly everything can be DIY or purchased complete.
All you need to make beer (all-grain): One pot big enough for your batch size, a nylon bag, and a heat source. And ingredients, of course. You could easily do a BIAB set-up for under $300 with all new equipment.
Having brewed for over 10 years now, I gotta say that I wish BIAB was around when I started, or even the Grainfather (or something like it). I've gone from small to big to bigger to RIMS and back down to small and simple in that time. I've spent more money than I want to think about. Keep it small, simple, and easy to use and you'll find you brew more often and enjoy it more. When you have to move things around a lot and spend nearly as much time cleaning as you do brewing, it can suck the fun out of it in a hurry. Just my two cents from an old guy whose back hurts for days after brewing on his 3 vessel system. (Which is why I just recently bought a Grainfather)