what should i wear during my triathlon swim?

I am doing my first triathlon in 5 months and am going to start my swimming training this week. What can I get to train in and race in? I don’t want to buy something expensive just to race in. I am thinking I buy one of those wetsuits that just cover your legs up…similar to the ones the olympic athletes race in. I don’t want to train in bulky swim trunks. I suppose I could go with the speedo…although I might be slightly uncomfortable at first.