One of my best purchases last year was a little MIG welder from HarborFreight. It was around $100 with coupons. It doesn't come with any accessories, so I bought an auto-darkening welding helmet for around $40, leather welding gloves, slag chipper, etc. also at HF.
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=98871
The MIG welder is flux core only with no gas option. This means you get a lot of splatter and slag, but you can always grind those off. I'm happy with the increasing quality of my welds on iron and steel. I used it to make the rear carrier on my scooter EV -- and most recently, a firewood rack for 1/2 cord of firewood. The little MIG welder runs on 120 VAC which is very handy since I can just use the current power outlet in my back yard.
Unfortunately a flux core MIG welder means that I can't weld aluminium (which needs gas), which is a bummer since the weight/strength ratio of AL is ideal for EV use. I need to upgrade to a gas MIG welder -- or a TIG welder. I'm leaning towards the latter but I really need to ge a 240/220 volt outlet installed since it's not worth trying to buy a 120 VAC TIG. But getting a TIG welder would be great. I could even weld titanium if I wanted to. :-) Maybe Santa will get me a Lincoln TIG welder for Christmas....
I use steel from a local steel reseller, Logan Steel. They sell surplus steel bar and sheet for $1 a pound, which is quite reasonable. Their billboards are ubiquitous in southern CT.
The other useful tools I'm using are an offset grinder to prep my welding stock. Also, I converted my HarborFreight compound sliding miter saw to be a metal cutting saw by putting in a 10" metal cutting disk. Very useful, especially when I'm cutting a lot of stock. What I like about my miter saw conversion is that I retained the ability to do 45° cuts (or any arbitrary degree) as well as relatively long cross-cuts, which a lot of dedicated metal chopsaws can't do.
So far, no problems at all using the miter saw as a metal chopsaw. The motor is well sealed, so I don't really expect there to be any.
Learning to MIG weld wasn't difficult at all. I had a friend show me how to ARC weld using his buzz box, but I think I could have figured it out entirely by myself. Wire welding is quite easy, almost point and shoot. The main issues are safety and prepping the material properly. There are enough training videos on YouTube and sites on the web where you can learn all the pertinent aspects of welding.
p.s. And no, I don't get any kickbacks from HarborFreight... I wish I did though, I spend enough at that darn place.
I highly recommend auto-darkening face shields. One of the reasons I got the cheaper MIG welder from HF is that it didn't include any accessories, such as a non-auto face mask. I find the old fashioned tinted face shields to be impossible to use. I know that after years of practice, you get good at setting up your pieces and then nodding your head just so so that your face shield flips down, but invariably your hand moves a bit and you start your weld somewhere weird.
With the auto-darkening shields so cheap, there's no point even bothering with that learning curve there.
Karen
p.s. this is also a test of the anonymous commenting system.
I've also been playing around with oxy-gas welding (currently oxy-MAPP). I've toyed with the idea of getting a full scale oxy-acetylene torch but it'd cost around $400 for the tanks and all, and I don't think I'd use it that much over the MIG welder.
So the flux-core gasless MIG and a future TIG setup seems to be an ideal combo, along with my toy oxy-MAPP for doing small projects.