For the pre-facelifted Barina (ie before MY04.5), the front badge is part number 9196806. Post facelift is 13111757, 13128241 or 13190975 (all the same part, just the number has changed a couple of times). For the rear, all years, it's 9198559 for the centre emblem itself.
As for where to buy, UK or Germany are the best bets, there was an eBay store called Opelise who used to sell them, not sure if they're still around. Failing that, try Autovaux or possibly Nevlock Performance in the UK. Nevlock, I'd probably rate higher than Autovaux these days, but apparently they seem to be able to get there hands on a lot of hard to find parts. I think you can really only contact them via their Facebook page though, but are pretty good to deal with.