As if you needed more ideas, here is a thought: because this is a supplement to your collecting and not a main focus, you might enjoy something less specific. T206 being my passion horizontals, SLers, etc excite me. If it were a side interest, I would probably start with just collecting old mill backs. It's a less specific focus that doesnt require a large time investment to find one of a very limited number of choices. In addition, you can still grab a SLer, HOFer, etc with an old mill back. Here is a great thread about the available OM backs:
http://www.net54baseball.com/showthr...t=92110&page=5
Alternatively, you could set a price point for commons and start picking a bunch up until you are inspired to move in a more specific direction. This thread is a wonderful example of what makes the t206 set so compelling... it inspires many people in many different ways. Make it your own and enjoy the ride!