Annette, Walter T Kelly sells one for about two hundred bucks assembled. All you have to do is paint it. I bought an inverter, I use off my truck battery when no electricity available like today.
I use it on most jobs. It really comes in handy on hives that have a ton of bees. Its hard to remove comb sections that have hundreds of bees on them.
Once you've vacumed a bunch, you are better able to see what you're doing.
A bee vac also comes in handy when dealing with aggressive bees.
If you don't have a vac, smoking them to move them off of the comb sections helps, but less smoke is better as too much may run the queen into some nook or crannie.
Make sure to take pics on your removal and have fun.