Pfaff model 360 is a lovely heavy duty machine, (has a free arm as well which is handy). Older Singers, Whites, Kenmores, Berninas, Necchis, etc are all good, but you want to look for a pre-1970's metal bodied machine (not plastic......grrrrr), metal bobbin, no electronics. You can commonly source these under $30 at thrift stores. These machines will have been manufactured in North America, Europe, or Japan. New ones are made you know where...
On any of the smaller portable machines, you are probably gonna be limited to a size 18 needle, which will handle up to a size 69 thread. You want something that will do a decent straight stitch, and maybe a zigzag. That is it. You aren't sewing a dress, and don't need a damn automatic buttonholer, or a bunch of decorative stitch patterns you will never use.
If you have the space, consider getting a true industrial machine that comes with a powerful clutch or servo motor, handles bigger needle (harpoons!) sizes (=stronger thread), good size table, more clearance under the presser foot (can sew thicker material) etc. The best part is that they frequently sell cheap. I paid $1000 for my walking foot Juki, but have seen them listed on Kijiji for around $500. Industrial singers are common- often see them listed in the $100-$200 range.
Any Buzzer that craves an industrial machine....I have two Singers that I will get rid of for well under $100 each! (Working machines with large motors, tables, complete). You gotta come pick them up though! The hobby got a bit out of control a few years ago...