Help: Searching for Vandersteen-like speakers...

There are a lot of good solid state amps out there. You would really need to decide on your speakers because some amps do work better with certain speaker loads and form a kind of Synergy.
The McCormack DNA .5 is a good choice. The Belles 150A Hotrod is an excellent amp. These are my two top choices in something you can obtain reasonably.
I used a pair of DNA .5's in a biamp for a long time with the 2Ce Sigs. It was an excellent combo with the Audible Illusions.
I then sold the Ce's and bought the 3A Signatures. The McCormack's continued to work well. Then I went nuts and bought a pair of 2Wq's and the 4-ch Theta Dreadnaught. This was pretty much a case of overkill in my room. Once set up, it sounds as good as anything I've ever heard and i've heard a bunch. But the point is that the McCormack's more than held their own in most respects.
As for your speaker recommendations, well, that's going to be tuff. The Vandersteen's are not very efficient and will not play that loud in absolute terms. They do go down in the upper 30's however. I really am at a lost for a good speaker than meets all of your criteria. To go down in the thirties with a 90db rating, it will most certainly have to be a ported design. Sealed enclosures will require more input power but will go deeper. Most ported designs really don't do much below 40Hz. Some people think they do but what you hear is the bump up before the crossover which gives an illusion of better bass than it really is---especially in the $1500 range. There are good speakers out there but they don't sound a lot like a Vandersteen. Meadowlark is a first order crossover but the Kestrel is not the speaker that the 2Ce Sig. is. Might look at the Shearwater used. I personally don't like its midrange but a lot of people seem to.
If you need the efficiency of 90+db, it's going to be tuff in that price range to get TRUE 35hz performance.
Might need to back up and look at Paradigm 100 series or even the Triangle Celius. Excellent speakers that can be found used for this money. Entirely different sound than Vandersteen but accurate speakers non the less. The Triangle has a tendency to be a little bright with solid state. You could drive it with an SET amp. It is very efficient. With all tubes, it sounds nice with extension down to about 40hz.

Bigtee, I currently use B&W DM602 speakers which I think sound damn good, but they only go as low as 52hz. Because of this I use a subwoofer, but I have to set the subwoofer crossover to high to capture all of the range and there is my problem. If the DM602 would go down to the 40hz range, I would be a happy man, but it doesn't and I'm not. I have checked out other B&W speaker in my price range and they all sound good, but none of them go very low. However, I know such a beast has to exist. I recently saw an Infinity Alpha 50, full range, tower that went down to 35, 91db and could handle 10 watts and the towers were at 1000 MSRP. If Infinity could do it, so could other people.

Bigtee, one thing for sure, Audiogon has been schoolin' me pretty good.

I'm going to chime in with one last post. DON'T believe manufacturers specs. If it is a ported design, it will have trouble going below 40hz ( not to say it can't but usually they will be very expensive). Manufacturers spec speakers with all kinds of figures and most are baloney. Your room also has a lot to do with this. I guess what I'm trying to say here is I've never seen a speaker in that price range REALLY go down that low. For example, the B&W 805 Nautilus was spec'd to go fairly low (less than 50hz). In my room, the best it would do using a spectrum analyzer was about 56hz at -6db. It dropped off like a rock after that. Most speakers in your specified price range are going to be ported as I've said before. At that price range, they will have a bump in frequency at about 60-100hz to allow them to produce much at 40hz. Pull out some old Stereophile magazines and check it out.
I would go with an accurate speaker such as the Vandersteen with a genuine low end. Any ported speaker is a hard match with a sub because of the phase shifts around the crossover. A sealed design matches better with a sub.
By the way, B&W makes several lower cost subs that I would think would match up reasonably well with your 602's. Try before you buy is my best advise.
I'm of the accuracy school. It is the primary reason I use Vandersteen loudspeakers. They are accurate. I also believe in phase correct and time aligned designs. You get a lot for your money with Vandersteen because the box ain't much. He doesn't waste money on a lot of wood veneers.
I was in your position some years ago. It is a learning process. I used ported designs for a while and I will never go back. But, the biggest thing is to satisfy yourself. Listen with your own ears and make your own decision. Nobody can do it for you. Good luck with your hunt.

Dynaudio Audience 72 is around your budget. These medium sized floorstanders are giantkillers for your money, don't pass a chance to audition them. They are 4-ohm single wired.
I succeeded driving them to a very high level of musical realism with a pair of 28W 845 SE-Triode monoblocs (Cayin 9084D made by Spark Audio). These are quite affordable here for me. But I understand 845 Triode amps are very expensive in USA. Good luck and post back your findings.

Even with speakers that supposedly do 35hz...it is recommended to crossover the sub at an octave higher...in this case 75 hz...because BOTH would be -3db down at 35hz...

A note on Vandersteens:although I do like their sound, they are not designed to be played even remotely loud, and their bass...although musical...is not the fatest or tightest bass around....for this reason...SS bass power is a must...a tube pre helps "round" things out....