I am not sure that REI or other camping stores would have exactly "butane" in those small (230g or 450g) disposable canisters. I suspect that all you will find in this size, will be butane-propane mix sold under the brand of MSR or Primus.
These small disposable butane-propane canisters cost more than green Coleman propane canisters and are only available in big camping stores - not in hardware stores. Cost and availability was the reason for me to convert my backpacker Primus stove to propane. Coleman cylinders are heavier but for car camping this didn't matter for me.
Considering the cost, in 7-8 weeks you will spend extra $30-40 on MSR/Primus canisters, and for this money you can buy a propane portable 2-burner stove.