That's a generous budget. You'll have more than enough light to play with.
The Streamlight RailMount 1, 2, or HL-X is the baseline I'd recommend, and each are also the budget picks. However, with each of these, I'd *highly* recommend that you make the extra spend for the Arisaka Defense Tailcap Adapter (there's two models, one for the Railmount 1 and 2, and a separate one for the HL-X), as it will most likely completely address the main weak-point with the Streamlight system (tailcap electrical contact).
A step up would be the Arisaka (yes, that same company!) 300- or 600-series, each of which utilizes the very under-appreciated Malkoff Devices LED drop-ins and VME head assemblies.
Stretch?
I'd hop on to Big Tex Outdoor (a very trustworthy retailer - just check out their raves in the P&S crowd...and yes, I've been a happy and loyal repeat customer of theirs since 2017, if not 2016) and pick up either the 18350 or 18650 Modlite PLH "Blems" -
Buy Modlite PLH-18350 Weapon Mounted Light Package | Contains PLH Light Head, 18350 Body & Tailcap, KeepPower 18350 Batteries, & Nitecore D2 Charger
www.bigtexoutdoors.com
Buy Modlite PLH-18650 Weapon Mounted Light Package | Contains PLH Light Head, 18650 Body & Tailcap, KeepPower 18650 Batteries, & Nitecore D2 Charger
www.bigtexoutdoors.com
These packages are excellent values, and will have you rolling with one of the most highly regarded rechargeable "all-purpose" WMLs on the market today (their OKW is more of a distance thrower for outdoors use: while still definitely usable indoors, the beam-pattern of the PLH is more well-suited for an "all rounder"). Add a McClicky (super highly regarded) tail-cap for an extra $20, if you like direct-switching, and you're all set for the light.
^ Now, the ModLite package will be both a slight financial stretch due to the tailcap consideration as well as the need for an appropriate mount (here, I'll again recommend Arisaka's products) - if you want a remote tape-switch, it's gonna cost you even more.
On the Big Tex website there is also a "demo" Surefire M600U Scout that's still available:
https://www.bigtexoutdoors.com/prod...600u-1000-lumen-led-weapon-light-z68-tailcap/ , whose $215 price includes a nice ADM Q/D Picatinny mount.
While the M600U doesn't have the raw power of the DF, it's still far from weak (if you want more throw [i.e. higher candela], look to the previous-generation Scouts instead - look to buy on the secondary market, which should have excellent pricing as guys unload their old stuff to upgrade to Malkoff/Arisaka, Modlite and the Cloud Defensive OWL), and bypasses what is perhaps the sole weakness of the DF: that very "dual-fule" setup.
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If you want something with a remote tape-switch (often just called "tape"), while the Streamlight items will come with, you'll have to add that as well as the appropriate tailcap for any of the Surefire based lights, including the Arisaka (you can make selections for that within the product's selection drop-downs - note that with the Arisaka lights, you can still meet the upper limit of your budget even with some of the tape options).
If you still have a few dollars to spare, the Cloud Defensive LCS (
https://clouddefensive.com/product-category/lcs/) can really help with tape mounting and cord routing.