I don't know how much he's looking to spend, but I have a Rainbow vacuum cleaner, and although it's expensive, there is no filter to clean and it really sucks a lot of stuff up. My inlaws vacuumed their house with their normal vacuum cleaner and then they borrowed our rainbow, and they got tons more stuff up!!
You fill the "bucket" with water and put it in the base of the vacuum, and everything that the vacuum sucks up goes into the water. Then, you just empty the water and all the crap that was sucked up, either outside or into the toilet.
I think it cost us roughly $1,200. We have had it for about 7 years but we have definitely gotten a lot of use out of it (still works great) and there is no bag/filter/dust to deal with.