Obviously if you don't see the board by yourself you have to trust the seller, on ebay checking the feedback of previous sales. If he had already sold windsurf boards successfully and/or it's a professional seller, you can buy with few risks.
Before bidding ask for international shipping rates to Romania (I do the same for rates to Italy even if is written shipping only in Germany). And know the way that carriers handle fragile items in your country, in Italy I received an used board with broken stern edge because of Poste Italiane (easily repaired with epoxy resin stick).
This way I've bought on ebay.it a Mistral Score 98 lt for 65 euro, a Mistral Score 112 for 75 euro (the one arrived broken), and an AHD Seal 88 to be repaired (even too much..) for 150 euro. Going out from ebay.de I've bought 6 new HotSailsMaui sails and 2 Fiberspar RDM masts, for good and cheap prices.