I'm always surprised at how many people say, "I'd like to full-time in an RV, but it is just too expensive." When we first considered selling our home and living full-time in an RV, we ran the numbers comparing the lifestyles (I am an engineer and like doing that).

Recently, I ran them again using my experiences while full-timing — and the results might surprise you.

Many of life's costs are the same, but each way of living has special costs. Your costs may be different, but here is a combination of my costs or U.S. averages and assuming either a house and two cars or an RV and one car.

Home — There are two ways to look at this. For a $200,000 home, you are either paying a mortgage or you are losing interest since you have your money locked up in the home (homes as an investment tend to be risky). This works out to be $1,000 per month.

RV — In the same way a house either costs in a mortgage or a lost investment, the cost of an RV can be substantial. We bought a new fairly standard RV, and the cost is about $400 per month.

Taxes and insurance With an RV, there is no house insurance and no insurance needed for the second car. There are no taxes or license fees on them. You do have to offset the cost of RV insurance and fees. This worked out to be a savings of $100 a month.

Utilities You don't have to pay for water, electric, natural gas, trash, sewer or cable when RVing. That is all included in your RV site. Phone and internet stays roughly the same. This worked out to be a savings of $175 per month.

Campsites — We averaged $33 per night for camping by using a combination of national, state, RV parks and occasional boondocking. This means a cost of $1,000 per month.

Maintenance RV life does require maintenance on both the car and the RV, but it is nothing compared to a house and two cars. They say that a typical homeowner spends 1-4 percent of their home value on maintenance. This one is more of an estimate, but I would say we save $150 per month.

Big items If you have a home, you probably have lots of things you can't bring along in your RV. We sold our second car, our big lawnmower and lots of smaller items like furniture. This money was invested, making us $100 every month.

Storage — We ended up having two storage units in two different states (don't ask) for things we wanted to keep. This cost us $225 a month.

Stuff You don't buy "stuff" anymore since there is no room to put it in your RV. So while you might frequently buy furniture, cutesy pillows, paintings and other home décor, you don't spend that money when RVing. While some people live to shop for clothes, you can't do that given the one-foot space you have in your closet for hanging clothes and the limited space for shoes. I rarely bought "fancy" clothes, and I lived in jeans or shorts. I estimated I saved $175 every month, but it was probably more.

Food Studies have found that the average home in the U.S. wastes 25 percent of their food. This is due to spoiled food or uneaten food. When you live in an RV, space for food is limited. It is rare to throw something out because you didn't see it at the back of your small refrigerator. I think you also tend to eat healthier since you are hiking in the outdoors more. Assuming an average $440 per month for two people, you save about $75 a month.

Vacation When you live in a house, you tend to spend a large amount of money for a big vacation every year. This means costs for planes, hotels and dining. When you are RVing full-time, you are on vacation every day. You spend money for things like museums, but the costs aren't that much. I assumed that I saved $125 per month.

Mail forwarding Mail forwarding isn't expensive. The service plus shipping costs was an average of $25 per month.

Gasoline Gas for the RV and car can be substantial. Much of this depends on how much you travel. For us, it cost us an extra $250 per month.

Working through this example means we spent the same when living at home or full-timing. And the reality was that it was pretty much equal for us.

Your numbers may be different, but don't use cost as an excuse to stop you from going full-time. Being able to travel gave us a whole new viewpoint and was well worth it!