I am thinking of learning blender and direct3d, however, the only problem I have with blender is I may not be allowed to sell games made with it. What is a good 3d modeling software that I could use to make models for games that I can sell? I'm looking for something affordable, maya is too expensive for me.

From the Blender site FAQ:

"Can I use Blender commercially?
Yes you can. Any creation you make as an artist with Blender is your sole property, and can be applied for any purpose you choose to. This also applies the Python scripts you write with Blender.
If you like to distribute Blender itself, you have to be aware of the GPL rules, which basically means you have to make sources for Blender available as well. However, in general it's sufficient to provide information that forwards to blender.org.
For a bundled product (blender file and blender player) we have to sort it out still, here a conflict might apply making the .blend file GPL as well. This information will be updated"

Of course, this would only apply to stuff you have made yourself -- files that others have created and you downloaded may have restrictions on how you use them. For example, I make much of my stuff freely available for whatever-the-heck-you-want-to-do-with-it but I ask that I be credited for it.

Scott

Depends a bit on if you need high-poly models or low-poly. I use Milkshape 3D, a 25 dollar low-poly modelling program, for my Half-Life 2 models. It's not so hard to learn (it doesn't have 300 buttons and thingies and all) and it supports a wide array of filetypes to export to or import from. There's a 30 days trial for it so you may want to check it out if that's what you're aiming for.