If you want to keep to your budget and want to keep using the MiniMe, you probably won't have too many options.
The microtrack is one of the few cheaper flash recorders that takes a coax digital input. The FR2LE doesn't (analog in only), so you wouldn't be able to use it with your MiniMe. Recorders like the Tascam HDP2 and Marantz 671 have a coax digital input, but are more expensive than your budget. I'm not sure there are any flash-based recorders in the $500 range new that can take a digital coax input other than the Microtrack.
The Sony PCM-D50 is a nice, hand-held size recorder that meets your budget ($450-475 new). I've got one and like it far more than the Microtrack that I also owned for a couple years. The D50 takes a digital input, but optical, not coax. You could use that with your MiniMe, but you'd need to add a digital format converter (like the Hosa ODL276) that will convert the coax digital of the MMe to the optical digital needed for the D50.
EDIT to say: if you're not totally wedded to the MMe, you might want to consider selling it and spending a bit more for an all-in-one recorder, particularly a busman- or Oade-modded one like the FR2LE, the 671, the HD-P2, or the Edirol R44. These would be in the $900-1200 range, but with the sale of your MMe might be in your price range.