If you root your phone, there is an app to wireless tether for free. If you are not rooted you will have to pay to use sprints wireless tether.

You can do wired tether through usb for free, it doesn't matter if you are rooted.

 

It means you have not activated the service with Sprint which you will pay for.

If you root you can use wireless tether and tether wireless or if you do not want to root you can use pdanet and tether via usb, both free of Sprint charges.

To get the full version of pdanet you will have to purchase that program. I've seen that cost anywhere from 20-30 dollars depending on any current specials they have going on. Both ways to tether work fine and you will not be charged a Sprint fee.

 

You can use the free version of pdanet, but it won't access https sites. You can also use Easy Tether, the full version of that is only a one time cost of $ 10. The guy may not have been lying depending on when you talked to him. The first two months the EVO was out people were able to wireless tether for free.

I've used both the free versions of Easy Tether and Pdanet and they work fine. I went with full version of East Tether because it was cheaper. Works just fine.

 

Before I rooted my phone, I used pdanet (free version) for wired usb connection. I did not pay for the https since I rarely came across sites that required it.

After rooting, I switched to WIRELESS tethering, which also has a free app for people with rooted phones.