Honestly been looking into this exact dilemma since the RF mount is still kinda closed off to third party autofocus macro stuff and its weirdly frustrating because the EF market used to be so diverse and I spent way too much time reading spec sheets and forum posts about how the R7s high pixel density interacts with older glass and whether third party protocols actually keep up.

• I think some of the older third party EF glass still holds its own in terms of sharpness vs the newer RF stuff
• Someone told me the autofocus hunting can be an issue when adapting certain brands compared to native glass tho
• IIRC the working distance on those older 100mm-ish designs is basically the same regardless of the brand you pick Not sure but I heard the communication between the adapter and the R7 can sometimes be a bit finicky with older firmware so you might need a dock to update things if you go that route which is a total pain. Its a bit of a rabbit hole but basically i found that market research shows you realy have to weigh the cost of the adapter against the savings on the lens itself. Just a thought since the native options are limited right now.

For insect and plant macro photography with your R7, the RF 100mm f/2.8L Macro is an excellent choice within your budget, offering superb image quality and a comfortable working distance.

This ^

Building on the earlier suggestion, using an EF adapter is definitely the way to go if you're trying to save money. I agree that the lack of third party RF macro glass is pretty annoying right now. I'm not 100% sure tho how the older third party options handle the R7's communication protocol. IIRC there are reports that some adapted lenses can't actually hit the maximum 15fps or 30fps burst speeds because the hardware can't keep up with the data exchange. Not sure if it's a voltage thing or just old firmware. Someone told me you might need a manufacturer dock to update the lens software just to get stable AF performance on mirrorless bodies... It's basically a trade-off between the lower price of the older mount options and the seamless performance of native glass. Just double check the compatibility lists for those older units before you buy.

Consider the RF 85mm f/2 Macro IS STM for a slightly wider field of view and lower price.