New vs. Used, Welders, Why?, etc....
New vs. used? Again, out here in the country we've got hordes of farmers and DIYers that'll bid up beat up old tools and such to ridiculous prices. Example: I paid $1300 for a new 3000 pound rated 6 by 12 flatbed trailer two years ago, just saw a couple 20+ year old ones sell for $1100 and $1200 at auction. By the time they get done replacing what looks to be the original tires they'll have spent the price of a new trailer for a rusty old one. My rule is even if you've seen it work and all documentation is included, don't pay over 50% of new price for it. Otherwise, better to wait for a sale and buy a new one with a warranty.
As for welders, I've got 220 @50 amps already wired in the garage for an electric dryer, just unplug that and plug the welder in. But I'm leaning to MIG and a lot of them don't need 220 anyhow.
As for why make my own stuff like sidecar mounts, my Guzzi Quota that I've owned for six months and still don't have hacked is exhibit one. The manufacturer of my sidecar is only 70 miles away, but they don't want to make rectangular shaped clamps to match the rectangular frame and their fitter suggested welding mounting tabs onto the frame. No way, we know nothing of the metallurgy of that frame and how to properly weld it! Another sidecar maker 1500 miles to the west lists a mount kit on his website, but admits he has none in stock and he's backed up for weeks. I have a feeling that'd turn into "bring the bike out here and leave it for several months 'til I get to it". I'm sure CSM sidecars in Pennsylvania could do a great job of the mounting, but same deal- transport the bike 1500 miles, drive 1500 miles home, drive 1500 miles back to CSM, drive 1500 miles home- 6000 miles driving with a trailer just to get a sidecar mounted! Fortunately there's a very skilled sidecar mounter within a hundred miles of here, but he's got a day job and a family and a garage full of projects already. But he was nice enough to take an hour of his time to sketch out for me a plan for a subframe that's way overbuilt for the job. So even though I could probably get by with modifying Motorvation's clamps to fit the square frame and drill a hole in the frame for an upper rear mount like the outfit to the west does, I'm going to try to do it the best way with a subframe. That means at least cutting the subframe materials and tacking them together with screws in hopes my sidecar fitter has time to weld them. If not, I'll have to weld them myself. And even if I wimp out and just modify Motorvation's mounts, I'm going to need a workbench and vise to hold parts down while I manipulate them and a grinder and probably a saw too.
So that's the sorry reality- we're not training enough welders, machinists, etc. so if you want something fabbed in the future you'll need to do it yourself. And given that full frame motorcycles are going extinct, if you want a sidecar you'll have to make a subframe or ship it across the country to one of the few remaining sidecar fitters. For less than the cost of that option I can set up my own shop and do it myself.