Agree with much of what has been said here. I don't know your background in taping, but one consideration not to be overlooked is the old adage "buy nice or buy twice". This advice is advice I should have taken myself but didn't. I had taped enough that I knew I would be taping a good bit and generally liked what it was about.... but ended up buying tons of different gear in rapid succession until I ended up with what I have now, Schoeps and DPAs.
I'm not suggesting you get Schoeps and DPAs - but I would say that if there is a set of mics you *really like* that is a slight reach for you (maybe, for instance, the Neumann 184s) it's worth waiting a couple extra months to get that rather than ending up making "incremental" upgrades.
The Naiant littlebox is a solid product that is probably worth the investment no matter what mics you get; it's small, easy to use, inexpensive, and high quality.
To that and the excellent D50, I'd get the absolute best mics *that you personally like* that you can afford. Meaning, if to your ears something less expensive or not from one of the best-known German/Danish manufacturers is your favorite, go that route. I have zero knowledge of the Milabs or ADKs, but those are two examples of slightly less "big name" products that many love.
To give a simpler answer to your questions, if you're buying new and you get a littlebox, that leaves you with cash for Pelusos or Busmans. If you're buying used and willing to wait, you can probably get some AKG 460s in that range as well. Again, it really depends on what you like. There is something to be said for buying new, in terms of warranty service and knowing how the product has been treated. However, I've bought both of my high end mic sets on this board in the YS and had zero problems.
Also, if you like the sound of themdix 1280s are in the range, new, and they have the advantage of being easily usable for low-pro work, especially if you get a Church $65 active cable and a small battery box.