AFAIK, BLU phones are factory unlocked as I don't believe carriers can relock them.
Is 4G/LTE data access a must or important or mainly voice/SMS for road travel? Which countries in Europe are you planning or frequently travel to? Typically, these devices will have the 4G/HSPA+ bands for US/the Americas OR global & Euro with the 2100 Mhz band being the most frequently used. You will need to decide what's more important with these (mostly) inexpensive lines of offering - like the Dash 5.0 just released, $99 USD shipped on #Bay ... (import/VAT to CDN address might be extra)
Use this site to check specs - http://www.phonearena.com/phones/BLU-Dash-5.0_id9018