There are lots of very low cost "MIG" welders such as this one for under $100. It claims it's gasless. But the girth of the torch and its lead look like it could feed gas. No gas inlet barb or hose is visible. But calling it MIG if it can't use gas seems like complete misrepresentation?
It is a "MIG" (Metal-Inert-Gas) welder in the sense that it does have a shielding gas for the weld - but the shielding gas comes form the flux core in the wire being vaporized during the welding process and not from a separate gas supply.
You'll note in the product listing "Requires flux cored wire " - because without the flux core there's no shielding gas.
shocked Deadpool face
Misrepresentation!? From Chinese junk on Amazon Marketplace!!??
The crux of the matter may be about Amazon
Jeff Bezos made the fanciful decision to open his business infrastructure to all comers. This created the Amazon Marketplace which has become a "junk shoppe" like eBay and AliExpress. You know it's the Amazon Marketplace flea market when it says anything other than "Sold from and ships by Amazon.com" under the "buy" button.
Amazon also allows anyone to use their warehousing/shipping infrastructure, so these Marketplace items often ship with Prime. Regardless, they count legally as not having entered the EU yet for purposes of safety and fitness certifications.
Better manufacturers have their equipment tested by a proper testing lab such as BSI, TUV, ETL, CSA, and UL, where they do a Big Clive tear-down (and then some). However, there are "voluntary" marks like CE and RoHS, where they merely promise they self-tested. These marks only bear on manufacturers are importers who are inside the EU, everyone else is free to stick the mark on anything. I call it "counterfeit", but that only applies if it's brought into the EU. And sitting in an Amazon warehouse inside the EU doesn't count for some reason.
Suffice it to say, when you buy off Amazon Marketplace, you're the importer. Making you responsible for assuring the CE stamp is valid. Obviously that does not happen, so this becomes a loophole for selling you substandard junk.
Unfortunately it also sets your expectation for prices, so you become biologically unable to pay 500 quid for a competent welding setup.
MIG means inert gas
The whole idea of MIG is to cloud the work in an inert gas - because the hot molten weld is extremely vulnerable to reacting with oxygen in the air. With steel, you can get by with exhaust gases from a gas welder or vaporization from flux from a coated stick. But aluminum is so sensitive it must be an inert gas.
Now with flux-core wire, they put flux on the inside of the wire instead of the outside of a welding stick. Whatev's. But this flux is certainly no more effective than on an electric stick welder, and that is wholly inadequate for aluminum.
How you would make this one work? If you're welding easy stuff like steel, the flux-core wire is simply the equivalent of the flux-covered welding stick, and the upgrade is that it is continuous. For challenging material like aluminum, I suppose you'd need to work in a glove box which you have filled with inert gas.
Novice user + cheap tools = path to failure
Welding is a skilled craft. One does not just pick up a welder and start making competent welds. An experienced craftsman can often work around the shortcomings of cheap tools. For a novice, to fight both the lack of experience and the tool itself is often too much. When you stack on the difficulty/impracticability of welding aluminum, forget it.
My suggestion would be get a membership in a maker space and do your work using their (hopefully competent) tools with their advisors on-hand.