DIY Build an Underwater Robot ROV and remote control

[Bubblesong]

So I am looking to build a simple DIY kit, for underwater ROV cheaply, before I invest in a more expensive kit, just to see what constraints I am working with. I want to be able to teach this to others, so I can't buy the more expensive kits right off the bat.
I found this one:
How to build a ROV — Utah Underwater Robotics
with parts list:
UUR ROV Parts List
The Home Depot parts list does not cost a lot, for the practice. The problem is some of the parts are discontinued, so I will have to substitute then update my own parts list. I live near DIY electronics, so I have hope I can find good or even better subs.
Has anyone built ROV from scratch? I understand the kits from overseas don't keep out the water.
Comments welcome from other DIYers.

 

[DennisS]

Not really DIY, just assemble, not cheap but a good source of info and thrusters

Bluerobotics.com

 

[wetb4igetinthewater]

@Bubblesong

Define expensive? Is this for the fun of it?

For our filming project, we are looking at using this one: https://bluerobotics.com/store/rov/bluerov2/ With the add-ons, we are looking at $5K.

There is some disruptive technology being developed right now that is going to open up a lot more applications due to plummeting costs (compared to today), great capabilities, and simpler logistics. You can put the Blu ROV in the water by hand, as opposed to needing a crane and larger vessel for a submarine.