With your current rigs, how much gain do you typically add?
Supposedly, M10 has cleaner gain than the R-09, so you could get the M10 first, and see whether you're satisfied with going mic-in and relying on the built-in gain. If not, shopping for a pre would be the second step.
Next factor to consider, how are your mics terminated? 2 x mini-XLR, 2 x TRS or exotic solutions like y-cable with 5-pin mini-XRL?
If each pair are wired differently, you need to decide which input jacks your pre should have, and possible rewire the mics to make them compatible.
I agree that the Sony pricing for Europe is annoying. Maybe it has to do with EU customs/taxes, the USD exchange rate also plays a part for sure. At the end of the day, Sony set this price because they think they can get away with it:
because Europeans are used to pay a premium for their brand,
because the depression hasn't hit us as hard as the US,
because the competition between retailers is less fierce and the market is more fragmented in the EU,
because online retailers, ebay and comparison shopping isn't as matured as it is in the US,
because EU retailers have a higher markup/gross margin,
I'm just guessing...