Posted By:
Glen VDepends on if you stick to ACC #s, include different backs, type 2's, etc.
The near impossible E cards would be the E100-2, E107-2, and all over-print backs. Otherwise most E issues can be found, with the less available being the E271 Darby Chocolates (~45-50 known?). The E's will probably be the most expensive of the T, D, & E issues due to the G&B, Texas Tommy, Darby, AWH, etc.
Likewise, ignoring the T231 Fans, the basic T issues can be found with the T208 Fireside and T4 Obak being the biggest hurdle (I consider the T215 Pirate a back variation). Adding back variations becomes very expensive and next to impossible (5 T207 Red Cross backs?). Non ACC #s adds the tough Derby Cigar and All-Star Baseball (really tough if you don't want the top trimmed off)
The only real tough D's are the Tarzan Bread and Clement Brothers, unless you include the Niagra Baking overprint back.
The H's have 3 years of Boston Garters, Welton Cigars, and Western Playgrounds. Better have lots of money to consider these.
The F's only big challenge is the Lummis Peanut Butter (1949, so you can skip this if you stick to pre-war.) The F-Unc add some tougher issues, but most can be found and don't cost too much.
Of course you don't have to collect every issue to be a type collector. Like Leon said, collect what you want.
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