Any welders in da house?
how much would you charge someone to fab and weld this frame???
Where is your cross bracing? Are you just welding the legs to the top? Or is it all pieces to be welded? Worst case welding it all from separate pieces it would take no more than 2 hours, 3 if you're very slow for set up. 200 bucks for a hobbyists or retired welder that does it in his backyard. See if there's a hackerspace near you, someone there can do it moat likely or even better help you do it yourself.
200 bucks for a hobbyist sounds about right to me.
My shop would probably charge more like 4-500, you're looking at at least 3 hours of work when you factor in cutting the material and finishing all of the welds like OP wants etc.
We'd probably TIG it, MIG would be faster and cheaper but you'd end up grinding it for an hour instead of having nice welds that don't need much done to them after the fact.