What proceses do You plan to do?
If You want to stick weld, get a used Lincoln Ideal Arc 250 or Miller Dialarc 250. They are bullet proof and weld well.
If You want AC & DC Tig as well as stick, get a used Miller Dialarc 250 HF, 300 A/BP or a lincoln 300/300 TIG. If You have a bit more to spend get a 250-350 amp Syncrowave.
For MIG the 250 amp machines from Esab, Lincoln & Miller are hard to beat for a home shop.
A fair number of these import machines are sold as "For Repair or Parts" on eBay. Regardless of the waranty offered [be sure it is parts & labor, and check shipping requirements] I have reservations about the reliability.
With regard to the import plasma cutters, there is a guy selling a disc on how to repair them, if that tells You anything.
I have been tempted by these 50-60 amp plasma cutters, but haven't bitten into this apple.