Stick welding is cheapest, and used AC buzz boxes are plentiful. I bought mine when I was still in high school (70's), and I've been dragging it around since then, though I hadn't used it since I moved out of my parents' house, also in the 70's.
Just fired it up for the first time since then a few years ago when my boys wanted to build some specialized workout equipment (glute-ham raise machine, and push sled - they're both college athletes). So I wired in a welder circuit to the garage, and taught them to weld. Stick welding is also the hardest to do in the sense that you have to control the pool at the end of a long rod, which gets shorter as you go, but it's still a long way from the hand to the puddle. At least with various wire feed processes, your hand is close to the work. But that equipment is a lot more money, and to weld heavier sections you need something more than a toy.
My old welder is in the right corner of the screen (Linde 230A AC only), and it has the very nice feature of a movable core transformer with a hand crank, so you can make infinitely small adjustments. But there are loads of old and current Lincoln 'tombstone' AC and AC/DC welders out there, and they're one of the old standards. DC allows more choices of rod, but to be honest, unless you're doing real structural welding, in other than flat or horizontal position, it's really not a concern. For common trailer repair and modification, a 200A AC only welder is fine, especially if it'll go as low as around 40A (for small rod, for thin material).
Oh, and if it's an actual critical weld, like a trailer hitch modification, I'll fit and tack it, and let either one of our production welders (structural steel fabrication company) or an aquaintance down the road do the finish welding. I do know my limitations.
My younger son welding his own glute-ham raise machine.
