Lets start with the most expensive one first--ventilation.
Hood--schmood, it's just a hunk of s/s steel with removable filters. Matter of fact many cities don't even require it to be s/s, just plain galvanized will do. You should buy this stupid hunk of sheet metal used, O.K.? However, its what's behind the hood that costs. Remember, I said ventilation system. Most cities/municipalities require a Mech. engineer to provide drawings for the whole system: How much air this system will remove, where it will remove the air to, and, how this air will be replaced. Most municipalities require a two hour fire rated shaft that connects to hood to the extraction fan. Where this fan will be placed--how far it is from the hood-- is directly proportional to the cost of the system. This is why your guy quoted you so high, without really looking at your place, he just picked the highest figure. If the shaft is only 8 feet long and goes through a brick wall to the fan on the other side of the wall and vents out into the back lane, it's not gonna cost much. If the shaft has to go through one or several load bearing walls, up a story to the roof, or make a left turn for a couple of yards and then a right, it's gonna cost a lot more. Then there's the make up air. If you remove air, you gotta replace it. This system doesn't require a 2 hr fire rating, but many cities will require tempered make up air . This means another fan sucking in fresh air, air conditioning it, and pumping it back into your kitchen so your guys can breathe. It's usually needing a 1 ton a/c unit.
Then comes the fire suppression system, or Ansul system, as the Americans like to call it. For every cooking appliance, you need a nozzle and pipe configuration that directs a stream of chemical on the flame. So for a 4 burner stove, you would have a certain configuration, for a deep fryer another configuration, for a salamander yet another. You also have nozzles in the hood plenum and in the shaft. This is entirely customized for the set up you have under the hood. While it sounds complicated, it's suprising low-tech: A high tension cable is stretched behind the filters in the hood and connected to the chemical bottle. This cable is "welded" together with lead blobs. If the heat gets too hot behind the filters in the hood, (ie."fire!") the lead melts, the cable snaps, the fans shut down, and you got one heck-uva mess to clean up after the fire.
The dish pit.....Whether you choose to lease your machine or not, it's the infrastructure that costs just as much or even more than the machine. You will require:
-A soiled landing table
-A pre rinse sink with gun, and some kind of strainer assembly to trap food solids before they go into the grease trap
-The dishwasher, of course
-A landing table for clean dish racks
-Municipality may or may not require separate pot sinks
-Storage for dishwashing racks
-Backflow prevention device for the d/w chemicals and /or the d/w itself
-Possible upgrade to the hot water boiler for your building
-Not required but practical: Overhead shelving for glassware racks.
The hood for this is nothing more than an upside-down box over the machine. Its not hooked up to anything. Every time you open the d/w, you get a cloud of steam. If you only do 3-4 racks p/hr, this isn't a problem. If the place is high volume, you get a lot of steam, and this wreaks havoc with the a/c system, causes mold issues, and generally makes the kitchen hot, muggy, and uncomfortable. The hood just traps the steam, and it condenses and collects in 1/9 inserts or is plumbed to the drains.
If you can buy this equipment (other than the d/w) used, so much the better. New is very pricey and has no direct advantage over used. You can lease the dishwasher, but the stuff I just mentioned is almost never supplied by the leasing company. You can swap out a d/w in a few hours, to swap out this stuff will take a day or more, provided the new stuff fits....
The dishpit should be located as close to the doors as possible so servers don't have to traipse through the entire kitchen when they clear off a table, and if the bar is sharing, close to the bar as well. Size of soiled and landing tables and size of d/w are dependant on:
-Serving style (tapas vs main dishes)
-If the bar will use the system as well
-Catering or sattelite dining rooms
It's a lot of information, I know.
Key words are :"..what your municipality/city/health inspector wants"... Every place is different, but what I just wrote you is pretty typical of most N. American municipalities.
Hope this helps....