This is coming from a beginner rod builder, but...
...my first built was on a Cabelas IM7 ($30)... And if we don't take into account the Shikari's I got at half price from Mudhole a while ago, that blank has probably the best price/performance ratio of all the blanks I used... That doesn't really mean much since I've only built about a dozen rods, but I've used G.Loomis, St.Croix, Shikari and Lamiglas and while Lamiglas takes the crown for the best blank (their XMG50 is AWESOME), the IM7 never let me down no matter what kind of crazy stuff I did: horsing a 20# grouper out of mangroves, pulling 50# braid till something breaks, etc...
C.