First, just to get some facts straight, butane will not vaporize below -1C. So, as long as you're staying a few degrees above freezing, you will get at least some pressure in a canister of butane.

The most common butane type of stove I've seen looks like the one in the below photo:

Note the butane canister in the photo, which is the type of canister used by this stove. Typically, the canisters contain about 230g of butane. Here in Los Angeles, CA, USA, the canisters are available for as low as $1.00 (USD) each.

These aren't the lightest stoves, so I probably wouldn't take them if I had to carry them on my back, but they're fine for picnics or home use. Here in the US, they're primarily used by the restaurant industry. These stoves and their canisters are about as cheap a stove as you can get.

A word of warning: If you use a large pot on this stove, the pot can reflect heat into the fuel canister. If the fuel canister gets hot enough, it can explode, just like any other stove. It's important to use a pot whose diameter is such that it doesn't significantly overhang the location of the fuel canister.

HJ