Since you know you want a new machine I won't make my usual suggestions about checking garage, estate, etc sales. Instead I would first recommend a trip to your local sewing machine store. Not a department inside a fabric store but an actual store that specializes in sewing machines. Sometimes they combine with vacuum cleaners (no idea why) but you should be able to find a listing in the yellow pages. If you can go on a weekday afternoon when they are least likely to be busy. Tell them exactly what you've told us and take the time to try several different machines.
You may decide that a few more features are worth a slightly higher price as sometimes a bit of automation can help. At the minimum you should have adjustable size stitches in forward and reverse modes, straight and zigzag, and buttonholing ability. The machine should also come with a zipper foot.
Singer and White both make decent starter machines. I've often seen the White model advertised in my area around $89. You can check the big discount stores after the sewing store - although eventually you'll need to take the machine in for service and those folks can also help you troubleshoot if you buy the machine from them.
Deb
