The Pool Weasel is basically a pump, small filter, hand truck, power switch, heavy duty extension cord, and some assorted minor plumbing and mounting parts.
I have seen similar homemade setups that use a trolley cart, instead of a hand truck. That way the filter doesn't have to be able to lean over. If you do that, you can use completely stock parts. Just make sure you get a trolley cart that is strong enough to hold everything. Filters that are full of water can be quite heavy.