Hi Dave
I'm going through a similar process right now. The only difference is I already know how to stick 2 bits of metal together with mig, tig and stick
I say "stick bits of metal together" because I haven't done any courses so I wouldn't be trusting my welds in anything where structural integrity is important.
Having said that if you get decent penetration and the thing looks solid, I would personally trust it.
Which machine you buy is predicated on what you would like to weld.
For me I want to be able to weld up mild steel and thin aluminium (1 to 3mm)
I was going to go for a unimig viper 185 which seems to be the pick of the litter as far as multiprocess welding machines go for hobby use but as I found out recently from some of my boilermaker mates is that to do tig on aluminium you need AC tig. Something to do with on one polarity it does the welding and on the other it cleans the oxide. There are youtube vids out there showing DC tig and you can see the pool of molten material forming an outer layer of oxide that prevents the pool from flowing into the work properly
The viper is DC only so tigging Al is out of the question. They say you can mig Al but you will need a spool gun because the aluminium reel is too soft to push up the entire distance from the inverter to the hand piece so they mount the spool on the hand piece itself.
Problem with the handspool/mig solution is that it's only good for aluminium at least 1/4" thick.
The other downside with mig and Al is that tig, once you get good at it, looks better because it's more controllable
With that in mind I started searching for a multiprocess welder that had AC tig and found a good lincoln unit but the price jumps to 2 grand from the viper's 1 grand.
The missus is all for it but she said I'll have to save the extra grand outa my pocket money
You also need to look at gas bottles for tig and mig. both processes need different gasses
I learnt mainly using stick as at the time mig and tig where only just coming out and the machines where prohibitively expensive and huge.
Stick these days is good for outside work on windy days as the gas shield gets blown away with even small breezes. One problem with stick at the moment is the rods are nearly as expensive as a head of lettuce
Here are links to both the unimig and the lincoln
Oh and pay the extra couple of hundred buck to make sure you get the bundle with all the attachments for all the processes including a welding mask
Unimig
https://www.machineryhouse.com.au/k0181dLincoln
https://toolkitdepot.com.au/lincoln-electric-powercraft-reg-200m-4in1-multi-purpose-welder-k69074-1/PS If you have any questions feel free to ask, I have been casually researching this stuff for a couple of weeks