@babygalll two dollar bills are not “out of print”. Currency of all valuations is printed when there is demand, and there isn’t enough demand for $2s to print them frequently. The government can, and will print a new run of $2s when there is sufficient demand, not on some kind of regular schedule.
One thing to remember is that printings aren’t the same as the “series” printed on the bill. The “series” simply reflects the last time the bill was redesigned. So the fact that the most recent $2 bills say “series 2003” doesn’t necessarily mean they haven’t been printed since 2003. $1 bills currently being printed still say “series 2006”, but they are being printed every month.
Though the last redesign of the $2 was in 2003, the most recent printing of them was from July through September of 2006. You can see the printing history on the Bureau of Engraving and Printing’s web site http://www.bep.treas.gov/section.cfm/2/431.
As to why they are rare—well, they aren’t. Not really. Nearly 250 million $2 bills were printed during the last run, and there are estimated to be about 750 million of them in circulation, worth about $1.5 billion. That’s less than .2% of the the total currency in circulation, which makes them rare compared to other denominations. But on the whole, with 750 million bills in circulation, I wouldn’t characterize $2 bills as “rare”. You’ll find that reflected in the price if you try to sell them. Currency collectors won’t generally pay anything (well, maybe $2) for them because they aren’t rare. You’ll have to find a real rube on eBay to get more than $2 for a $2 bill. If you really want a stack of $2 bills, don’t pay for them—stop at the bank and ask. A lot of times they will have a stack of them that have been turned in by vendors, and you can buy them for the low price of $2 each.
Regardless of the actual number of them in circulation, $2 seem more rare than they truly are because people don’t like to circulate them, for some of the reasons stated above; lack of room in the cash drawer and so forth. And there are some people that simply hate them, though I’ve never really understood why.