That's $300/month, so definitely not unrealistically cheap. I was just traveling in Croatia where I bought unlimited one week data SIMs for $12.

In Italy, the local SIMs were more expensive, so I used my GlocalMe G2 global hotspot and bought a $30 1GB/1 year worldwide data plan. I used about 500MB on that 4-day trip, so I have data left over for my next trip.

GlocalMe data plans generally cost about 5X less than the price of ATT roaming plans and about 2X more than many local SIMs, so it's often worth it for the convenience of not bothering with the local SIM purchase - especially if you're visiting several countries.

For me, the GlocalMe approach of buying a block of data which can be used over a year is a lot more appealing than paying a fixed price of $10 per day. It would be great if the vendors would make both types of plan available.