[Oldendum]

Download the manuals from Lincoln. Compare the parts lists. I think you'll find little difference in major parts aside from cosmetics, depending on the age of the machines.

Lincoln makes models with different names on the faceplate for different markets. Welding supply stores would carry the SP. The others go to different retailers so that they can have "different" products and the consumer can't price-match.

You can get a new Hobart Handler 140 for around $500. at some of the farm/tool stores. If you have 240 volts available, you can get a Hobart-refurbished Handler 190 for $529. though they are not always in stock.

http://www.hobartweldshop.com/servlet/the-132/refurbished-mig-welders/Detail

A refurb 140 is $400. and they are in stock:

http://www.hobartweldshop.com/servlet/the-133/refurbished-welders/Detail

Build a cart.

 

[Oldendum]

When I bought our first welder (not taking into account a $40. Speedway stick welder joke), I was going to get a 120V welder like a 140. Decided to step up to a 175 Amp class, just in case I wanted to do a little thin aluminum welding. Glad I got the 240V welder and ran another circuit in the garage.

Never did try aluminum in the Lincoln 175. Cobbled together a nice TIG rig instead.

Lincoln and Hobart are both good in that class. The only other thing I'd recommend you investigate is a Thermal Arc/TWECO Fabricator 141i. It's an inverter that can also do TIG and stick welding.