Wareagle,
You can go 100' out, but you will get some voltage drop in your machine, but you can compensate by turning your machine up. The main issue with a 100' extension cord is cost... that large gauge wire is expensive!!!!

 

I bought the Chicago Electric flux/gas welder from Harbor Freight. Was an online only purchase and was on sale for $158. It is a 220v which I easily made a 10ft extension to my dryer plug which is 2 ft from my garage door. Yes, it does weld, but the settings are 1min/1max/2min/2max... which basically means dialing in a good weld is hit or miss... I burn through more holes than I do getting a good spot weld.

I have laid down some really nice spot welds with it... and then in the same breath have had to spend 15 min. grinding down some real crapola.

If I had to do it again, I would drop the extra 250 on the miller-matic 140.

For now, I will grind when I have to... Time is money, but all I got is time on this project.

 

I have the Millermatic 140 which was an upgrade to my old mig welder. What an amazing difference!

 

I've never used any of the cheapo welders. I use a millermatic 250 but I have thought about getting one of those china tig/plasma/stick combo units. My dad said he has one of the cheap flux cored welders that I could take to college with me if I wanted to do some work while I'm here but I never used it and neither has he. I'm not even sure what brand it is, he got it on some kind of trade. Maybe when I go home I'll try it out and see how it compares to the miller.

 

I got a lincoln 125 for $500. i use flux with it mainly because i can't use gas, it has no provisions for it. Works fine for me for jobs that don't exactly require a nice neat job. Flux is messy.