What is the cheapest hardwood to use for kitchen cabinet face frames?

I want to build a set of kitchen cabinets for my sister because she really needs them. I also do not have a ton of money but I want to create something nice. What wood for the face frames would be my best bet keeping in mind the cost.

The two least expensive hardwoods are oak and maple. Oak is less money and fairly to work with as hardwoods go.

Use Pine. It's plentiful and inexpensive.

Poplar is the cheapest hardwood, but it also looks the cheapest.

Oak and maple are the least expensive and both have a nice grain for staining. Only use poplar if you re going to paint it. Pine is too soft for cabinets.

I have built plenty of nice looking kitchen cabinets using nothing but plywood with hardwood veneer. Oak or Birch. I think the birch plywood is slightly cheaper but there's not a big price difference. All parts of the cabinet can be cut from the plywood if cut neatly.

Go with Oak.

Pine is too soft, and can be a pain in the rear to work with. Flooring contractors will often charge MORE to install Pine than to install Oak because of it's tendency to break and splinter.

Alternately, just get some of the modular cabinets sold by many outlets. My wife and I are installing Ikea Cabinets and find the cabinets to be fairly simple to assemble.