I also have full frame Nikon (d610). It’s not easy finding quality glass for $200, but I did buy a 60mm/2.8 micro-nikkor used off eBay for ~$250. Takes great photos. Since it’s a full frame without crop factor, sometimes I wish it were longer. If you’re shooting from the top down and want to be dwelling in macro land, I would go with 90-100mm.
You can probably find an old manual Nikon 55mm Micro for about $200 or maybe an off brand with similar specs. I started with the Vivitar 55mm macro myself. That lens is probably 35 yrs old. If you want auto focus, then you will have to shell out more money. The Tamron 90mm macro is a great macro lens with auto focus. You might be able to find one for about $500 bucks used. You can try eBay and haggle. I always do this. If you want to go even farther, then it will cost quite a bit more. I have the Nikon 200mm Micro. Absolutely love this lens. Great for all macro photography, but not cheap at all.
See if you can find any mom and pop camera stores in your area. They sometimes have good prices on older lenses. I got the Vivitar 55mm for about $100. It is a fantastic lens if you have the patience to work with it. I believe auto focus is overrated in macro photography anyway. My 200mm has auto focus, but I only ever use it in manual, even for the pictures of my fish.
Nikon 105. New versions are pretty expensive. The only difference is Auto focus and stabilization - and these feature I always turn off.
So finding old version for cheap would be a good option.