Prepaid 3G/4G connection

[Mirosuke]

Okay, here is my thing:

Normal guy, don't have data plan on phone. (Got a unlocked smartphone tho.)
Have a tablet as well.

What I want?
I need a device that allows me get into internet (pretty much a data plan) that would work on my phone (might ask why not just get a plan, can't so long story) but also make it work on my tablet as well...

And one more thing:
I do not want attachments AKA NO contracts for YEARS. NO, no...no. So pretty much PREPAID.
Whatever I use, is what I spend.

Coverage:
Hawaii, lol.

Been doing some research and came up with...
Verizon Jetpack™ 4G LTE Mobile Hotspot 890L
and this T-Mobile® Sonic 4G Mobile HotSpot

but they seem to be available by signing a contract... but then:
MIFI® 2200 (Virgin Mobile) - They got prepaid cards with plans for each month. It displays as $99, but I can get it cheaper at Amazon.
So basically (I'm assuming) with that thing above, once acquired, you just go to their website, activate it, top-up and enjoy the 3G? My only fear is that would not cover where I am now, lol.

--
Doing some more research, Walmart made a exact copy of the device, except it IS from Walmart now. Internet on the Go Mobile Hotspot by Walmart and you can buy their Prepaid cards.

Anyone experiencing this or can help me out?