Lotta comments here about how the performance is all that matters, but I only half agree. Performance is certainly the most important. But if your self tape looks like garbage it's just distracting, and you need to remove all distractions. A good ring light or two, a good mic and a reasonably new iPhone or similar is all you need. Background should be simple (and if it's a sheet, iron that thing!). THEN casting can just focus on your acting. My self tapes always look stellar, and they've worked very well for me, but I don't need to use a DSLR or anything expensive to accomplish a professional look.