I've got the cheap Acuity pullcart that I bought for 30 bucks last fall.
I figured that it paid for itself after 10 rounds, and it's still in good shape.
But a couple weekends back I purchased a stand bag, as I judged that my right shoulder is in good enough shape again to carry a bag, along with my overall improvement in leg strength and walking capability over the past few months. My big worry about carrying a bag was how I remember how carrying a bag when I was young used to kill my shoulders by the end of a round.
The bags they make now are much lighter, and my shoulder has come out fine.