If you really want to make a professional looking project, stay away… far away from Avery products or anything that is a "label". Stickers scream amateur work.
I have done production runs of 300 units or more, all in house. My suggestion is to go with print-on DVD's/Blu-rays instead. I have had great success with using the Epson family of printers that have DVD trays built in (Artisan series). While that line is now discontinued, I believe that there are newer units that will print directly on product (Expression line?). Epson has software that comes with the printer that makes printing on DVD's extremely easy to do.
I have also learn how to use InDesign, and have created my own cover art templates in a variety of case sizes. Use a heavier gauge paper product, and the covers will look like something that is produced commercially. My choice beleive it or not… Costco's Photo Paper. Inexpensive, heavy guage, and looks perfect to present to clients.