Posted By:
Al C.risafulliMike, the cheapest prewar cards are whatever I happen to be selling at the time. Conversely, the most expensive prewar cards are whatever I'm interested in buying. Of course those cards change as my tastes change.
In terms of a good start for prewar, I'd humbly suggest building a subset of 1933 Goudey cards in midgrades. The set is large enough that you can slice it and dice it any way you like: HOFers only, portraits only, action images only, certain teams, etc. Heck, there's one 54 member (I can't remember which, I'm sorry) who only collects the ones with blue backgrounds, and you know what? They're beautiful.
33 Goudeys are both plentiful and popular; if you ever lose interest you'll have no problem unloading them at a fair price. However, in the mid grades, most of the cards are still affordable.
Best of luck either way. It's a slippery slope; before you know it you'll be addicted.
-Al