Although a lot of people don't rack to a secondary, I find it gives me something to do to make me feel like I'm still busy with the brew.
So a 5 gal carboy ($15-$20 brand new) is a good purchase. Also, I would switch to at least a non-hopped LME or DME and add your own hops. Plus most of those kits come with specialty grains to add some complexity to your beer. If you don't have an hydrometer, get one. Another good investment is a racking cane and syphon with a bottle filler. It helps to keep aeration down while transferring to the bottles. I hope this helps some.