Today is the day I seriously look at a cargo bike
 

I find I keep trying to convince myself that I need another bicycle, something with greater hauling capacity.
I want to move to using a cargo bike, as well as other bikes I have, more and more; and use the car less.
Ford discontinued the US version of the Fiesta and Focus (I have a Fiesta hatchback) in 2019 and this year, worldwide production of the car will cease. Parts in the US are already beginning to become more limited and by 2025, all US parts stock for these models will be gone and manufacturer support could just stop. The global supply shortage of everything hasn't helped. All that said, I need to get riding more and driving far less, so today I'm looking at a Yuba Mundo from 2013. It's inexpensive and not an e-bike, just what I'm looking for. I'm not in the position to drop more than $800 on a newer/different model, and I do all my own maintenance, so this older Hi-Ten steel frame may just be the ticket.
I'm not really happy about the 14mm axle rear wheel being a freewheel unit, but I haven't read about, nor have any of my mechanic friends seen a Mundo with a bent axle. Other than that, I really want that frame. I don't have kids nor will I, but I want some cargo hauling capacity greater than what I can carry on my Univega with a set of panniers. The Mundo will make even getting groceries far easier than using the Univega. Eventually, I'm not going to have the car and I'll still want to have the ability to do some hauling. Heck, I've seen folks carry lumber on a Mundo, something I certainly can't do even with my seats down in the car. I have always been a firm believer in the bicycle fitting in as my primary mode of transportation; I only got the car because I've become a bit lazy in the recent years, and arriving to work soaked isn't pleasant. I have a folding bike and public transit for really bad weather days, a dedicated commuting bike, a few Sunday ride bikes and I still have space for more. Feel free to convince me to bail or convince me to pull the trigger on the Yuba.

Maybe consider a trailer to use with your existing bike, that way you can tailor the hauling capacity for the job at hand. I really like the Burley flatbeds, they seem really versatile. Sometimes you might only need the panniers you already have, sometimes you need one item so you just take the trailer, sometimes you need them all like for a big grocery run.

I have big panniers for the bike, a single wheel burley trailer, and little panniers for the trailer. It's quite a lot of stuff when they are all filled up!

Well, the Yuba has landed. The seller let me know that a trusted mechanic at one of the city's better shops has worked on it since 2017, so that really sealed it up for me.
The Mongoose that was linked is currently unavailable and I couldn't even see a price.
I have a trailer, a BOB knockoff that is really good, but I find it to be a PITA when doing some shorter trips. I know that I could haul a lot of stuff using my trailer and my bike with a set of panniers, but I've gotten sick of that. I wanted a grab-and-go bike that had much greater capacity than what I currently have.
Now it's here, it needs some work. A full tune-up at least; possibly a new chain and freewheel, though what it has now works fine, but those gears are getting stretched and it won't be long before I'm swapping out all of the drivetrain. I have a much better crankset I can replace the SRAM one with. Saddle needs replacing, along with grips. Needs new brake pads for the V-brakes until I get a new set of disc wheels built. I'm going to use the Yuba rear hub (I'd love to find a new one, but I don't think that's possible.) Front hub is going to be a Shutter Precision disc dynamo hub so I can hook up a set of lights. Eventually it will get disc brakes, of course; a friend is giving me a set of Avid BB7s.
Right now the bike has a set of worn, but still serviceable WTB Thick Slicks. I am definitely swapping those out for a set of Continental Contacts, as big as I can get.
As for the cargo bit itself, I think I'm going to set about to designing something that can carry a bunch of different kinds of loads, in a modular sort of way (side baskets, vertical carry, even a deck for a wide-load). I'd like to be able to carry our Sea Eagle inflatable boat and all the associated gear, for a day out paddling; we'll see how far I get with that.
I'm looking forward to getting this back on the road and putting it to some use.

I paid $750 for my Mongoose Envoy (new) right in the middle of the Pandemic two years ago. They were hard to find then but I thought the situation had improved. Not being awful, but I hope you got that Yuba real cheap because it doesn't sound like that Ace wrench was doing it any favors. Don't spend a ton on it. If it's as bad as it sounds you might try to find a used Envoy! I hear you re: trailer life. I have a long suffering Bob Yak that goes out weekly but still there are times when it is too much. The panniers that are OEM with the Envoy have limitations and I have a link somewhere to better bags that a creative type bought and modified to be used on a cargo bike. I'll see what I can scare up. Don't be a stranger and don't be hasty.

I mentioned the parts I'm going to replace because I do that with every bike. The chain isn't stretched, but the freewheel has a bit of wear.
A friend of mine is giving me a set of BB7s. I'm going to build new wheels mostly because I love doing it, but also because it will give me a baseline where I'll start. I really got the bike for the frame, and yes, I got it pretty cheap.

"Currently unavailable"

Cargo bikes don't seem to sell well in my area. There have been two like new Envoy for sale in my area for $500-$600. The bikes have been listed for weeks and ads are still up. Same with some Kona Utes. Ads have been up for weeks. There was even a long box Bakfiets for sale for $350. Unfortunately it was about 4h drive from me. But the ad was up for weeks till it sold. I personally wanted an electric cargo bike and bought a used Radwagon 3 for $400.

Electric alternative that doesn't break the bank, $1399 or $1700 for dual battery:

How Does It Do So Much But Cost So Little?