What I like about a lot of the DIY Harbour Freight/Princess Auto vapor blasters I've seen on YouTube, is that instead of the water and media sitting in the machine, it drops down into a bucket underneath the machine. From what I can tell, this would make media changes much easier, as it's simply a matter of swapping buckets.
I have never looked at the HF vapor blasters, but how does the water/media come up out of the bucket to the blast gun? Does it just get sucked up or is their pump in the bottom bucket? You really need to agitate the media to keep it dissolved and free of clumps. Even with my VHT machine the media will pack down if I leave it sit for a while and then you have to jiggle the pump a bit to get it working. I bought an additive that really helps keep the media from packing down. But you just gave me an idea I may try on mine at some point to make evacuating the media easier.