Have you been eye-balling the Canon R6 Mark II, but held back by its hefty price tag? Or maybe you've been considering the R8 instead? Why not pick up the original R6 at the same price or less than the R8, and get the benefit of built-in IBIS, more advanced controls and longer battery life. The main difference between the R6 and R6 Mark II is the overheating 'fix', the other changes are quite minor. If you don't need long runs of continuous shooting, you can save a lot of cash by going for the original R6.
The headline features of the S5 II is of course the introduction of phase-detect autofocus, but brushing up your manual focus skills could save you 800-1000 when picking up a used original S5. This will allow you to get that same oversampled 10bit image and tons of dynamic range at a much lower price of entry.
The Fuji X-T5 can shoot 6.2K internally, but does so with a crop. If you're fine sticking to full-size 4K, the X-T4 offers the same 4K, 4K/60 and IBIS at nearly half the price second hand.
Although the new Canon R50 has the advantage of uncropped 4K, it also costs 1.5x the price of the M50. Furthermore, there currently is a much larger lens ecosystem of affordable APS-C lenses for the M50 than there are for the R50. If you're on a budget, getting a second hand M50 might be the most cost-effective way to get into filmmaking.
Canon has been phasing out their expansive line of EF lenses at breakneck speed in favor of their new RF mount lenses. This means that many lenses that were top-of-the-line just recently, have now significantly dropped in price on the used market. And EF-mount lenses can be used on all of the aforementioned cameras, if you get the right adapter.
Used gear from retailers
If you're not looking forward to meeting up in someone's garage late at night, or the risk of getting a defective body or lens, another option is to take a look at some of the second hand offerings from local retailers. You often pay a bit more, but you do get a camera or lens that has been serviced by professionals and often a limited time warranty.