Smartphone tethering

Anyone have experience in tethering a 3G/4G smartphone to a machine for internet access? My business is pretty much "on the road" for the time being and I'm in the market.

What are prices like?
I already have a Verizon plan, so I can either switch for free or pay an early termination fee. Worth it?
I don't have Bluetooth. Can this be done via WiFi or USB?

I've tethered my Android phone via wifi (it acts as an access point) and USB. It's super easy to do. For me it's worth it just out of convenience. On T-Mobile, I don't think you have to pay for it, though I'm not 100% sure they like you doing it.

I have Verizon with a Droid. The stock Android OS has tethering disabled but installing pretty much any other ROM fixes that. USB tends to work better for tethering so I use that.

Note that 3G is pretty slow (around 150 Kbps) for internet standards, on top of possibly having poor signal in some locations. It should work well enough for quick tasks, but don't expect big downloads to transfer very fast. 4G with LTE is around 10Mbps up and down, much better if you can get it.

This is for work, not play. I won't be downloading huge files or hosting game servers. I will be replying to lots of e-mails and doing admin tasks on our website. 2GB/month should be more than enough.

Also, I won't be rooting or modding or jailbreaking anything.

Installing a new android rom makes your life on the phone much more pleasant in my experience. Paying for tethering is, quite frankly, bullshit. It's a scam, and you shouldn't do it. Almost every android smartphone already has the hardware to do it, and you've already paid for the bandwidth, and it has been upheld in American courts that you are allowed to install "hacked" roms to your heart's content. So stop being a pansy and don't pay $20 a month for something that you've already purchased.

Also, it works best via USB.