Several options are available for discount welders. First, I'd recommend
that you decide what kind of rig you need, and what price range you can
afford for a discount mig welder.
Display & open box mig welders are available at a good price
Discounts are are available a lot of places. Consider buying
the open box display welders at a home supply store or welding distributor.
These mig welders are out there at a substantial discount, but they are all but
new. They might have been handled by people for a few weeks, but they are
essentially new mig welders with their manufacturer warranties in place. If you
want a discount welder, this is a good way to start.
Reconditioned MIG welders
Reconditioned mig welders are a good buy when you're in the market
for a discount welder, and can often be had at local welding supply houses at
good prices. The difference between a reconditioned mig welder and a used one is
that someone has gone in and worked over critical parts to make sure everything
on the welder works pretty much the way it ought to.
You don't have to buy it sight-unseen that way. I have bought a mig welder
or two this way and got a good discount off of new, with some assurance that I'd
have a good product.