There are two aspects to consider here.
First you may really need a phone upgrade.
And to check that your movil communication provider prices for movil internet services.
I highly advise a phone with any android operating system superior to 4 (as they work pretty well and fast). Creating a hotspot is really easy. Also if you have a pc that does not has internet connection and no wireless card you can use an USB cable to access internet on the PC.
Your movil services provider is of most importance. Some companies sell internet devices that reseble USB sticks, with a montly cost. But then you will need your laptop always on, and a router to connect a tablet if you wish so.
The cell phone can easily provide the same services for the same cost, so there is no need to carry multiple devices.
Now, all most every phone service provider offers plans of internet usage. Many providers affer internet service with common phone plans. Maybe you already have access and you did not even know. Personally i prefer pre paid service. So i have exact control of how much i surf on my phone, and buy extra credit if needed.