Man, I would love to celebrate with you, but in all honesty, it sounds like you're in over your head. I know you said it aint your first rodeo but several other things you said really make it sound like you aren't prepared for doing this big of a job.
First, you mention that it's your biggest job ever. And I know it's easy to get excited when you get a big job like that. But anyone who has actually experienced doing a lot of big jobs like that will usually tell you that they are often the most problematic....the ones where you have more potential for things to go wrong.... the ones you will get the most call-backs for. Having done quite a lot of jobs like that I will tell you that I still get excited when I land them, but honestly, I'd rather get 5 smaller $10K jobs than one big $50K jobs any day. On the big ones, you own them. Anything that ever goes wrong; settles, dies, quits watering, stops working (lighting), you're going to be getting a call on your cell phone to come over and fix it ASAP. And if you think you're so good that nothing's going to go wrong, well then I guess I should just stop writing. I'm totally wasting my time then......
Second, $100 for a design? What kind of design is that? Who is the designer? Is this person really trained landscape designer or landscape architect? I've contracted out for literally HUNDREDS of designs over the years. And I've never had a good quality design by a professional well trained designer or L.A. cost less than $500-$600. And usually it's more than that! You're seriously going to do some cheap $100 design for a house that is $1.5 Mil? Honestly, I think it's the homeowners you're working with who are the ignorant ones here. Just the fact that they think they could get a really well done design for $100 is laughable. That would usually scare away most of my clients if I told them our designs were that cheap.
Third, you mention you're wanting to do all this in 1 week? 5 days? That concerns me in many different ways. It concerns me because if you're really going to get all that done in 5 days that means you take some serious short cuts. Or the other option is that you've drastically under-estimated how long this project is going to take you and therefore probably aren't charging enough and going to loose your a$$ on the job. I guess maybe you're 4 guys are faster than the rest of us or something. And I haven't seen the design. But in general, here are some production times for a job like you're doing:
200+ feet of boulder retaining walls 4 feet high
4 Days. For an couple really experienced guys and a big track hoe and loader.
I don't know how many fountains and what kind or style. But even a modest rock bubbler fountain will take us most of a day to install. And you said plural fountains? So let's say 2 Days.
A court yard
Not sure what that means. To me, that means an area with some nice seat walls around where people are going to spend some time. But whatever it is, figure at least 1-2 Days
Over 400 plants, 8 Trees
That would take us a good Day and a half with 4 guys. Unless they're all 1 gallon plants. And if they are all 1 gallon plants, that's not going to be a very impressive job.....
If you're planning to do even a half-way decent lighting job - on a $1.5 Mil house - that's something that's going to take a good day or more to do. If you're doing it quicker than that, either you're really not installing very many light fixtures (which again, won't be very impressive) or you're just going at it half-a$$ed and slamming stuff in the ground without much care. Go to the lighting forum and ask the guys there if you think I don't know what I'm talking about. Ask them if they think you can do a nice quality lighting install in just a few hours on a $1.5 Mil. home. You'll get laughed out of the forum.
Now again, it doesn't say how big. But we've done a lot of those and I haven't done many that took less than a day. Many took 2-3 days to do.
500 sq feet of pavers
This is the part that really baffles me. We do a LOT of paver jobs. And unless this is a boring rectangle shaped patio with no curves or cuts on it (which again is pretty freakin' boring and not very impressive) then it would generally take at least 3 Days to do a nice 500 sq. ft. paver patio. If it is a pathway, those take even longer, usually, because of the curves and all the extra cuts
And a full irrigation system
There aren't a whole lot of guys on Lawnsite who have installed more irrigation systems than we have. This is something I do have quite a bit of expertise in. I was a speaker at the 2010 Rain Bird select contractor conference. I was selected to represent the NW region as one of 15 members of the Rain Bird Contractor Advisory Council. I know irrigation pretty well. So unless you guys do it a lot different than most of the rest of us do, a full irrigation install on a good sized property will usually take a good 5 days just by itself.
So that's about 19 days, by my count. Again, this is without seeing any of the details. But how do you expect to get something like this done in 5 days? Am I missing something? Maybe this is the smallest irrigation system ever or maybe you're just installing 4 spot lights and that's what you're considering a lighting system. Otherwise, I don't get it.
I hate to rain on your parade, buddy. I'd love to help you celebrate. But it just seems like you're ill prepared to do a job like this and aren't working in reality.
If I'm way off on my production times, post a reply with how long you think each of these projects are going to take.