What a steal!
I should have spent more time at the yard sales this summer... If you're looking for a first project, I highly suggest something done with knits since sergers do so beautifully with them! I did a simple A-line skirt - something like this pattern would be nice and easy: Kwik Sew 2805
. For fabrics I used Juliette double knit from Hancock (feels nice, but got a bit pilly with washing) and Ponte di Roma from Joann, which probably holds up a bit better. Kwik sew also has nice knit top patterns, so I've heard - I have a few of them, but I haven't taken the plunge to sew them up just yet!
Anyway, enjoy, and don't be afraid to play around. I'm still kind of afraid of rethreading my serger - but I've heard the best way to get over that is to just practice practice practice! Have fun!