This is what happens with all Atlus RPGs of note:
1. Comes out at $50, sells decently.
2. Major stores wind up with lingering copies and sell them cheaper than MSRP
2 1/2. That Circuit City thing was a massive fluke and I'd not base average Atlus prices on the fact that you found Disgaea for $5
3. Joe Blow finds out months later that the game he ignored actually rocks and pays more than retail for it
You'll likely have a chance to pick it up at a decent price at some point, but that time will be short. However, Atlus has made it clear that very little will be shipped outside of their pre-order amounts. If you don't want to dance around, just pre-order it or pick it up early. You get a soundtrack if you pre-order anyway (a packed-in second disc, since someone asked).
I'm getting this game and have had it pre-ordered for months now. It's been my most wanted game for this entire year and then some... its announcement even got my ass in gear for my MegaTen fansite idea (
www.digitaldevildb.com).
As for the guide, $20 is a steal. Brady and Prima guides often have countless inaccuracies. This one is well written (largely attributed to the Japanese guide it is based on, but if that means I get a good guide, then so be it), detailed, has extra (unnecessary, but interesting) information and is freaking 400 pages with two bookmarks and a poster. The walkthrough itself doesn't even start till like page 72. It was worth the extra $5.
I got the guide in the mail over a week ago and was expecting to get the game tomorrow. However, the shipping date slipped a third freaking time. Now it's shipping on the 14th according to all major game sites.