DC will do stainless. Alluminium requires AC.
The difference in price and skill required is significant, so work out if you really need AC?
Me?
I got a cheap used unbranded DC for less than £200 (used, which is almost more reliable than buying new when it comes to cheap Chinese inverters)
I then passed this on, and bought a used parweld AC, at about £450.
You'll probably need to budget around £200 for a rent free tank of argon (and deposit) also and some money for a mask, gloves, and consumables.
The UK mig forum will help further if you sign up there.