Pfaff Smart 200C sewing machine,
I was seduced by the price and the features, I too have had some trouble and I'm onto my second one which is going great.
The first one had a mind of its own, when it went into reverse it did a couple of stitches and then went forward on its own, so it went back to the shop. I am happy with it, I love all the features, especially the overlocking foot and the faux coverstitch.
Babylock BL4-736 overlocker
I got this second hand on trade me for $70, Its a four thread, no differential feed or rolled hem, (a rolled hem from my Babylock dealer is $70). I'm too scared to put anything too heavy in it having munted my old overlocker too many times
It goes pretty well and the dealer said I'd got a good deal when I took it in for service.
It did straight stitch and zig zag, it was a birthday present from my parents 15 years ago. It had been well used by me and my friends over the years to make clothes, hem trousers and jeans and make curtains, duvets, you name it. I even sewed my finger with it
Eventually I outgrew it.
got this at the local Tennis Club garage sale, it was great, it did stretch stitch, three step zigzag, all the things my brother didn't. It didn't have a free arm, which is really useful, especially for childrens clothes.
This was Grandmas overlocker, it was a great workhorse machine, it is a three thread machine and I thought I really needed a four thread, now I'm not so sure, it didn't have differential feed but it seemed to handle knits better than the Babylock. It can only sew one layer of microfibre and can't do towelling, I know this because I bent something inside of it trying to sew microfibre and towelling. Luckily my Dad was able to fix it (each time)!
(not sure of the model number, but its nearly 40 years old) Mums machine which I've had on long term loan, it handles pul and microfibre like a dream, it purrs like a kitten, I love this machine, I learnt to sew on it. It has pattern cams with fancy stitches, no three step zig zag or stretch stitch. It weighs a tonne.
Another good place for second hand machine reviews is http://www.zigzaggers.typepad.com/