I think the EF 28-135/3.5-5.6 IS is a good beginner. You can find a very good one used for about $300. At that price there is little negative to it. It has always been a good walk around lens so you probably don't need any more lenses at this moment. The EF 50/1.8 II is even cheaper used, somewhere around $80 or even cheaper. So get a EF lens that you get auto focus.