Here's a comparison between what the two brothers in terms of clothes they owned in S1:
Dress/Plaid Shirts: Dean=10, Sam=11
Sweaters/Long-sleeved shirts/hoodies: Dean=0, Sam=10
Unique T-shirts: Dean=0, Sam=8
Coats: Dean=7, Sam=4
So, in total, Sam had 36 articles of clothing (not including generic T-shirts, jeans, suits and costumes), whereas Dean only had 17 (not including generic T-shirts, jeans, suits, and costumes). So, even if we take into the count that Sam wore unique T-shirts instead of generic Ts in S1, Sam still ends up with more clothes than Dean has (mostly because for every shirt he has, he has a long sleeved-sleeved shirt or a sweater too). Though, Dean had two extra jackets (the third he lost in the pilot, so it hardly counts).
Clothing Survivability S1-S4:
By S3 we only see 1 of Sam's original 8 S1 Unique Ts
Likewise for Sam's sweaters and long-sleeved Ts...out of the original 7, only 1 makes it to S4
Out of the 4 Polos and Henleys introduced in S1, only Dean's grey Henley makes it to S4 (and it is doubtfully the same Henley, just the same colour and style).
None of Sam's S1 hoodies make it past S2 (though a new one is introduced briefly in S4)
Out of 21 S1 dress and plaid shirts, 5 make it to S4
Out of 11 S1 coats, 5 make it to S4
I'm so weird.