Most all of the major brands are great. If you are keeping your costs low then you may find yourself deciding not to go for all the bells and whistles. Remember that the sewing machine vendors also have used sergers from those who traded up ... and you can get a real good deal that way.
I have a Pfaff serger with coverstitch that I bought on sale years ago. I have to manually thread it but that isn't difficult to learn. [Though I did write up my own color coded directions as I know I think differently than any manufacturer.] It is a real workhorse and I love it. Even if I inherited a LOT of $$ I don't think I'd get a new serger. I'd go to a quilt retreat instead.