The Sequoias have generally been on sale, it is an older model year and it was the base model but Specialized has been closing out a lot of that stuff because currently they haven't made any new models and might be moving away from steel again (boooo!!!!)

I can agree on the comment on specialized headsets owning 3 of their bikes but the good folks at Cane Creek have you covered as does Chris King and White Industries and many others. You just need to measure and have your local shop order you something which you don't have to do right away if the base model uses sealed cartridge bearings (which the pro module does) if they use caged bearings then replace even a Cane Creek 40 is a fine option if you are looking to save money.

The frame cracking I haven't yet seen and I have sold quite a few Sequoias. Other frames most especially aluminum have cracked but steel not so much.

The bike itself has some lower end parts on it but the frame itself would be a decent candidate for upgrading especially at the price.

I would certainly test ride the bike first but having ridden the Elite and now owning a pro module I am building up I can say I liked the bike and geometry and was excited to own one.