Does anyone know the name of the real estate company offering a fix price to sell properties.

All agencies will try to charge you a percentage of the sale price usually.
This is not a law, and you can set the terms of the Sale authority as whatever you like.
Agents won't tell you this of course, and they will always try to get you to sign the "standard contract", and pay them a percentage.
If you want to pay them a flat fee for selling the house, just ask them if they are willing to do it this way before the contract is signed, and if they say yes then write the amount on the contract and cross out the sections where the percentage of sale would go.
$5k is a good number; they probably won't be interested for less than that.
Also, don't forget to tell them that they can pay any advertising costs out of that.

I just saw the website for changing places. Why do real estate agents always wear red ties in their advertising guff??

Laws vary from state to state!  As such some of the below may not be accurate in your state.

"This is not a law, and you can set the terms of the Sale authority as whatever you like." 

"and if they say yes then write the amount on the contract and cross out the sections where the percentage of sale would go"

$5,000 and pay for advertising.  Guess some Sellers get what they pay for? 

Setting a flat fee.  Does that really give the agent an incentive to get you the highest price based on a  comparison with % professional fee?

As always make sure you do your own investigations. 

One thing is for sure you can contact the REI based in your state for accurate consumer advice.