OK - I located a pre-programmed Europe Map card (SD or microSD/Adapter combination) that should work in your device.
This is a link to the Garmin UK site, and you MAY be able to purchase the map card directly from there, but you MAY be redirected to the Garmin site for your area.
When you get to that page, make sure you select the "microSD/SD card" option - in the pull-down selector if you intend to order from that page.
And if you like, you can double-check that the Nuvi 250 is on the "Compatible Devices" tab (I see it on mine).
Also, depending on what kind of shops and stores you have in your area (that carry Garmin GPS devices), it is possible that they could have a card in stock - and you could purchase it there.
Installation is simple - just plug the card in (with power off), boot up the device, then check that the maps on the card are "enabled". After that, it should work fine.
Please let me know if that works for you or if you have any trouble with the links.
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