If your cell phone works overseas (and not all do), your wireless carrier is happy to sell you an international plan that typically includes a small amount of minutes, texts and data at what feels like a pretty inflated cost. (The cheapest option from AT&T: 120 megabytes of data for $30 a month, $10 for 50 messages, $30 for 80 minutes, for a total of $70 per month per phone for a fraction of what we’re used to at home.)

Apparently, if you don’t use your phone much, you might be fine with that. Given the way I use my phone—to scan email, translate signs and menus, find my way around, coordinate plans with friends and family, book restaurant reservations and check opening hours for museums —I couldn’t imagine paying so much for so little.

The good news is that you can get a lot more for a lot less, as long as you can get your hands on an unlocked phone. Fortunately for us, my iPhone was no longer under contract and we had an old iPhone 3 that my daughter could use, so AT&T sent instructions on how to unlock each one. A friend lent us a Samsung he’d purchased for overseas travel.

I unlocked our phones the day we left for Europe (I was still able to use it in the States that day, as per usual). Once we landed in London, we found our way to a little mobile phone shop just across the street from Harrods and picked up a SIM card for five pounds (about $8.50), which included a five-pound credit for talk time. The gentleman behind the counter inserted the new cards, showed us our new phone numbers and told us where we could buy a package of minutes, texts and data (just around the corner at a news stand, as it tuned out).

Our British numbers worked even after we arrived in France, but I wanted more data than the small plan we bought. Two blocks away from our apartment was an Orange store where another nice gentleman sold us SIM cards (for five euros, including a five-euro credit) plus calling/text/data plans. For 30 euros each, Daughter and I got plenty of minutes, texts and a full gigabyte of data for the month we’re spending in Paris. Hubby, who is not as entranced with the online world, got a less generous plan for 20 euros.

You can, by the way, buy SIM cards at airports, train stations and lots of other locations from kiosks or news stands. I highly recommend finding a mobile phone shop that has someone to help you set up your service, though, especially if you’ve never done it before.

My plan paid for itself just on our recent road trip to the D-Day beaches. I used Google Maps navigation as a GPS to get us from the edge of Paris to every location on our agenda and back again, complete with turn-by-turn voice instructions. That saved us the $12 daily rental fee for our four-day trip.