For cheap, no idea. You'll save tens of thousands over buying and owning a car, but they're still $$ to buy.

Bicycle Belle is, I'm told, America's #1 Urban Arrow dealer.

They’re Dutch bikes, also known as cargo bikes. Not too cheap though so maybe you will have to craft one yourself. Have a look at the sub r/cargobike for make shift versions

They are expensive. Do you really need that much space up front? For kids, or moving your apartment? They can be hard to store in the city. You can get most of the way there with a long tail, or a Clydesdale fork slapped on an old hybrid or MTB.

Hello! Bicycle Belle in Somerville near Porter Square (right on Cambridge city line at Oxford/Beacon Street) is the Boston Metro Regions primary cargo bike retailer.

They are a woman owned shop, and have everything you need for car-replacement bike riding. Also everything you need for the whole family on bikes (kids helmets, bikes etc.). They do not carry anything outside of cargo/city transportation style bikes. No maintain bikes, roadies, etc.

The people who work there are great. They have inventory. You could go today and walk about with a wagon bike. Or, order direct.

Can't recommend Bicycle Belle enough!

Those bikes are sometimes called:

• Cargo bikes: straight forward name for their function
• Box bikes: straight forward name for their form

They are good for: moving cargo, transporting kids if they aren't of an age to bike independently, grocery hauls.

They aren't great if you rent on or own a small property as it is tough to secure them with out a fair bit of space.

Other kinds of bikes that are good, especially if you are looking to transport kids, are "long tail" bikes that have extended frames over the rear wheel.

And there are a lot of modifications to regular bikes with front and rear racks that can handle quite a bit, especially with some e-assist too.

None of these options are particularly "cheap". But maybe you want to tell us some of the things you're trying to do with a box bike?