You may already have considered this option, but I’ll put it out there just in case: Teleconverters (not to be confused with extension tubes) can be a somewhat less expensive option for obtaining a bit more reach. They have their downsides, of course. Here’s an article that discusses the main pros and cons. (for canon)
https://www.eos-magazine.com/articles/lenses/canon-extender.html
Hope this helps,
William
