If you are trying to stick within that 4k budget the various thin filmed options are going to be best for you.
There is the Harris L3 Thin filmed Green $3195, or the Thin filmed White for $3495.94
Or the ITT Elbit thin filmed Green for $3258
I'd also recommend the Wilcox L4 G11 army mount along with the Ops Core Fast Bump helmet both can be had at right around $620 together
this will explain the tubes in better detail
The Pinnacle and the Omni VIII are very similar tubes. They were both built for the military’s Omni VIII contract. Obviously at the time L3 Warrior systems won that contract before they were acquired and merged with Harris, however they are very similar. The biggest differences being that the ITT/Elbit Pinnacle, has a slightly thinner film it generally has a slightly higher photocathode sensitivity. (Brighter Image) We will see lower Halo Values from the Pinnacle as well. As far as spots or artifacts go, we will generally see a little more of what we call “peppering” in the Pinnacle units than the L3Harris OMNI VIII. “Peppering” is when you see a few black spots that are too small to be considered actual spots. These spots are almost imperceptible and can only be seen against a white wall or background typically. Some people don’t like peppering or blemishes in their image but honestly in practice they will generally not affect the overall performance of your system nor are they indicative of a poor performing system.
L3Harris generally has slightly better resolution which means you have slightly better detail when looking at small objects especially when viewed under magnification. We more often see small spots in the L3Harris system of “.003 to .006” in size. While we do not accept tubes with those spots in zone 1 (The center and most important part of the tube.) We do allow up to 2 spots in zone 2, and up to three in zone 3 (The outermost part of the tube). While some ITT Elbit Pinnacle tubes have a slightly audible whine, the L3Harris tubes are pretty quiet. You generally have a Higher Halo and Lower Photocathode sensitivity.