Welcome to TS!
I'm sure others can chime in with specific recommendations, but I'd swap out the MiniMe > R-09HR with a standalone record that acts as preamp, ADC, and recorder all in one. I, for example, use a (quite outdated at this time, but still very functional) Fostex FR-2LE.
You should be able to pick up an all-in-one recorder for under $500 used, for sure, and probably new...though I'm not up to speed on current recorders. That should leave you a good balance of budget to dedicate to mics. And don't forget you'll blow ~$100-200 of the budget on accessories like mic cables, mic mounts, mic stand, etc.