to buy or build a trailer?

As far as Missouri goes, so long as it is under 16' (and I believe that is tongue to tail) all you have to do is take to any inspection station like you would take your car or truck to. Where I go, they said about all they look for is an identification number of sorts to make sure it isnt a stolen trailer. And so long as the lights work and you have brakes if it has two axles that you are good to go.

My welding skills are decent, but I am not so sure that I would build one from scratch. I tend to overbuild in critical areas and doing that may take enough extra time to make it not worth while. 

If I could weld everything from both sides and in the flat position I would not hesitate one bit to have it on the road. That takes alot of extra time vs a skilled welder welding it up out of position. 

You may watch craigs list and see if one pops up for a decent price. Right now steel is high.

There are benefits to both options.  If you have time, then wait to find that cheap trailer to build off of.  With time you will be able to find a used trailer to your liking and pick it up a lot cheaper then building one, especially that size.  But, by building one yourself, you can make it to fit that need exactly.  When I started my build, I based my design off whatever trailer I could find.  Now that I am almost done, I wish the trailer was different.  But I know that I would have spent a lot more money building it my way then I spent on that used one.  Being on an extreme budget, I know I made the right choice in my case.

I have been looking for a used trailer but havent found anything that sits my fancy. I will likely build one. If you just want a trailer bet you would be fine with a found one.

I just went through this process on my build. I found a trailer that had a dropped axle, leaf springs and shocks. I think it was from an old Ford truck. Anyway, I figured that this would be a good start and if I had to make any changes at least I had some parts to begin with. As it turned out, when I set the tank and firebox on the trailer and set them off to one side of the trailer, the trailer leaned on one side. I ask a question here on this forum about springs and got a couple of responses but didn't get my question answered so I contacted a company that makes leaf springs and had a set made that would level the trailer and still give it a smooth ride. When all is said and done I think I still saved money by going this route. Hope this helps you.

You got a good deal!

I done both.  I prefer to build.  Saying that don’t rule out looking for a good used one for the axle and tires.  Those new get costly.  I also used the small one from harbor freight, but want go that route again.  

Good luck and show us the pictures.

Randy