Sounds like you are looking at Gas Metal Arc Welding process - GMAW, also commonly known a MIG (Metal Inert Gas) welding.
A 110-Volt, single phase machine (140+ Amp) with 75/25 mix of Argon/CO2 gas and 0.023" to 0.030" wire should do most of what you mentioned, welding 3/8" and thinner carbon steel. I recommend staying with well known brands like Miller, Lincoln, Hobart, ESAB/Tweco because replacement parts and service are easier to get for them lesser known import brands.
Downside is the brand name MIG machines prices start near $600 (with reguator.) Also need to add around $200+ for the gas bottle. Prices vary depending on bottle size and discounts. It is best to call around locally to compare prices.
Do not buy a cheap flux core only machine. Any MIG machine can do flux core wire, but it is messy and will wish you had the solid wire with gas.
There are also multi-process machines that will do MIG, stick, and TIG.
These machines are more expensive, mainly because they require addition cables and electrode holders. The stick welding function (Shielded metal arc welding - SMAW) could be useful on thicker steel or welding outdoor where the MIGs shield gas may be blown away by wind.
On these lower cost machines, the TIG (Gas tungsten arc welding - GTAW) function is pretty limited to fixed current DC lift-tig. This might be useful on thinner sheet metal or tight places where the MIG gun won't fit, but the TIG torch will, and maybe to learn basic TIG.
As you go up in price you get more output power, functions, and higher duty cycle.
The ESAB Rebel EMP 215ic Multi-Process machine they have been prompting on Power blocks Extreme Offroad looks nice if you want to learn to weld the different process. This is a dual-input machine so you can plug it in a 110-volt outlet and MIG weld up to 130 Amps @ 20% duty cycle or plug into 230-volt outlet and weld up to 205 Amps @ 25% duty cycle.
http://www.esabna.com/us/en/products/ind...=9504&tab=1These seem to be selling for $1437 on cyberweld.com or $1435 on weldingsuppliesfromioc.com
Both web stores have good prices on welders.
Duty cycle is the amount of time you can weld in a 10-minute period, so 20% is 2-minutes welding, 8-minutes cool-off time. These ratings are at max power output, so normally you will be welding at a fraction of the max output and duty cycle will be higher. The welder instructions should have a chart of the duty cycle at different outputs based on the input power used.
When I was looking up the machine prices, I noticed Cyberweld has a Tweco Fabricator 181i Multi-process machine that is only $599
http://store.cyberweld.com/tharcfa18miw.htmlMachine looks nice, but I think it is 230-Volt input power only?
I have never used one of these, but it has good reviews on the web site?
