The hobby had high expectations in '08 for last year's NL ROY, Ryan Braun, driving up the TAC of his benchmark 05 Bowman Chrome Draft Auto RC every month leading up the start of the season; $128.93 in Jan, $144.18 in Feb, $155.62 in Mar and $168 in Apr. Braun had a slow April, batting just .276 with 3 HR & 17 RBI in 105 AB, but has turned things around in May, hitting .298 with 10 HR & 19 RBI through 5/24. His BCD RC dropped off this month due to his mediocre April stats, averaging $143.04, and has yet to recover it's value. If you want to buy Braun's cards, don't wait too long because they'll probably start to jump again in the very near future. In '07 he hit 34 HR in a short 110-game season. According to espn.com, he's projected to hit 43 HR at his current pace.
Brandon Webb was a distant second to Jake Peavy in last year's NL Cy Young award race, but he started this season off as a clear favorite ahead of the rest of the pack. He put his perfect 9-0 record on the line on 5/21 against the Marlins, and despite pitching a decent game (7 IP, 6 H, 3 ER, 0 BB & 7 K's), picked up his first loss of the season. Webb's 03 Ultimate Collection Auto RC #'d 250, arguably his best rookie card, is averaging an amazing $148.76 TAC in May (a Gold version #'d 25 sold for $419.99 on 5/13!). His Ultimate Coll rookie cards are pretty scare, and before this month, the last one that I saw sell was back in Oct-07, and it went for $57.19 (and that was when he just completed a 16-10, 3.01 ERA season!). If you didn't already pick up Webb's key cards, it may be too late. I'm guessing that most (if not all) of his potential value is already built into his current TAC's.
Interesting Note: Jon Lester's 06 Bowman Chrome Auto RC had been averaging in the $20-25 TAC range this month. On 5/19, the day that he tossed his no-no against the Royals, one sold for $87.52! The next one that I saw sell, on 5/25, went for $23.36 (the same price level as before his no-no). What an example of hype affecting the market!