When purchasing your tank cutter, you should consider three things:
How often you will need to use the tool
The task you intend to use it for
Your budget
How often will you use the tank cutter?
If you are only planning to use your tank cutter once every so often, a less expensive tool with a hardened steel blade, rather than a high speed steel blade should be sufficient.
On the other hand, tradesmen using the tool everyday may find a tank cutter with a more durable blade more suitable.
What will you use the tank cutter for?
You should check the product specification of your tank cutter to ensure that it can be used to cut a hole of the necessary size. The capacity of the tool is the range of different sized holes a tank cutter can make.
How much should you spend on the tank cutter?
The cost of a tank cutter depends upon the durability of the tool and whether or not it is designed for extended use. A tank cutter with a blade made out of high speed steel will last longer but will be more expensive.
Tools with hardened steel blades are a lot more affordable and are better suited to DIYers.