Canon's mirrorless lens ecosystem is only good for people with high budgets, which $1000 isn't in the world of camera gear. APSC RF mount is in a particularly bad place with very few native lenses and nothing third-party. If you're looking at switching systems, why not look at switching brands at the same time?

EF has a ton of lenses, and used ones lose value slowly. If you buy used EF lenses, you'll likely get most of your money back if you decide to sell them to switch systems.

I was in your situation recently.

10+ years ago, I had sold all my Canon kit including a 5DMkII and some EF L lenses and I wanted to pick up photography again. I was luckily not committed to a specific brand since I didn't have any of my kit left so I was free to look at other platforms. I had a few friends with cameras and tested some different platforms out but ultimately settled on Nikon.

I currently have a full frame Z6II mirrorless and I like it very much. It's lighter and more compact than my Canon setup was, and I also feel like the lens selection and price (both Z and F) are better than it was when I had Canon. My favorite part of mirrorless is the focus peaking. I find myself using it along with manual focusing for about half my shots.

Look around at other platforms like Nikon, Sony, OM, etc. before you commit because it would be a good time to switch of you did want to. If you stay with Canon, I definitely recommend looking at mirrorless.

Canon latest mirrorless bodies are awesome and also good value (but stay away from the R100). As others have said, good native RF lenses are expensive. They have also cheaper options, but what they miss is the good value middle ground usually represented by Sigma and Tamron. One big upside is the EF to RF adapter, that works very well and lets you use the lens you already have before investing. Remember that a lens remains with you decades, contrary to a body, and paying a bit more could really be a good choice in the long run. Just my view, a bit in contrast with many steering you away from Canon. Quality wise, there’s no difference between brands: most importantly a camera should disappear in your hands and be really ergonomic - go in a shop and handle them all!

If macro is your game, it might be worth looking at micro four thirds. The sensor is smaller than your current sensor, which will result in more depth of field for a given f-stop. A lot of micro four third lenses, even non-micro, tend to have very short minimum focal distances. There's a slew of used lenses available for fairly reasonable new prices and the new glass is generally more affordable than other systems.

As others have said, switching systems is going to be pretty expensive - especially when all the other mirrorless systems are fairly new. After micro four thirds, Sony's e-mount has been a long the longest. Both mounts are very open, so there's plenty of third party glass available. If you're looking for a deep catalog of used glass, these are the mounts to look at. Canon has refused to let third parties use their mirrorless mount and Nikon is being fairly protective of theirs (limited third party options to fill niches that Nikon doesn't have native glass).

As a final thought, if you're fairly happy with your current body you should probably just buy a macro lens for it. Buying a used macro lens, even if you sell it in a few years, will result in less expenditure than buying new glass and/or changing systems. MPB and KEH are both good places to buy used glass, offer free warranties, etc.

I used to have a Nikon d3300 (bought on Craigslist with 2 kit lenses, plus bag, and accessories for $300) for 6-7 years. Then I wanted to do nicer portraits so I got the 35mm f1.8 for like $200. Then switched to the Sony system 3 years ago because I wanted to do more wildlife which would've required a new camera body because d3300, while an awesome camera, was not it for autofocus and fast shooting. Because I'd need to invest quiet a bit into whatever I chose next anyway, I decided to go with an a7iv, and have been really happy with it. It's perfect for all the stuff I was doing with my Nikon, along with the wildlife capabilities I was looking for, and for my needs I probably won't need another camera body (unless this one stops working).

I'd recommend if all you're looking to do right now is macro, your current body is likely sufficient and you'll probably find nice used macro lenses for it on a budget (<$500). I'm don't have experience with canon so I can't recommend anything specific, but I'm sure Google can help with that part. If you do decide that you are ever hitting the limits of your current body or are thinking about more expensive professional lenses (think >$1200), that is when I'd consider switching up a mirrorless. Either way, I definitely don't think you should invest in a new DSLR body right now.

Also - if you're looking at new mirrorless, the canon system right now is kind of expensive when it comes to nice lenses. I think Sony is the cheapest because of a lot of 3rd party options. But the price for the bodies is more or less the same. Then there are the m43 brands which I don't know much about but might also be a nice option.