My favorite is my featherweight! It sews a wonderful straight stitch and does well on multiple layers of even heavier fabrics like denim.
I also like the inexpensive Brother machine from Walmart. I passed mine on to a friend who did not have a machine. I had used it for over 3 years with no problems (other than broken needles from sewing over pins-my bad! or broken thread from letting it get wrapped around the spool pin when going too fast near the bottom of the spool).
Either of these would fit nicely into your budget. The Brother has several built in stitches including zigzag while the featherweight will only do a straight stitch unless you have the zigzag attachment.