I don't think "cheap" and open gun belong in the same sentence! If you want something under 2000.00, you are going to end up with a used gun.
Now keep in mind that open is just a division so you could actually use a production pistol in that division no problem. You would just be at a disadvantage! If you want a properly built new Open gun, you are probably looking at 3-4 K to get one + taxes and accessories.
I run a Czechmate which run around 3400-3600 and the other gun to look at would be the Tanfoglios or STI's. They come right from the factory ready to go. Freedom Ventures has the Tanfoglios and STI's. Take a look at their site.
If you want someone to build you a gun from scratch, then the sky's the limit for what you want to spend or the platform you start with. If cost is a big concern, go with 9mm as the brass is much cheaper!