Stick with either Miller or Lincoln professional units ( the Hobart ...now part of ITW group ...is the "retail" Millers. The retail Lincolns are the ones you find at Home, Lowes etc )
The best bang for the buck right now are the Lincoln industrial Power Migs
POWER MIGŪ 140C MIG Welder
Currently there is a rebate ( cash or auto darkening helmet .....the helmet is worth far more than the cash rebate so you should go for the helmet ) for the Power Mig industrial units bringing it down close to the cost of the retail units. The helmet you get as freebie is from Lincolns industrial line so it far better than the $100 ones at Harbour Freight
The 115 volt unit will have no problem with 1/8" wall tubing ...if you ever plan to do aluminum go for the 230 volt unit ...worth the investment
As far as gas / self shielded flux cored goes the MIG for your application is the best choice . The self shielded flux cored actually can weld heavier material on these smaller machines , but conversely cannot weld auto body as easily due to the high penetration characteristics of these wires
One 1/8 tubing you can get very nice, low spatter welds with the self shielded flux cored...just takes more technique