I'd agree with the other comments here...buy cavity backed and what you can afford. There are even some golf shops that will sell used clubs that were trade ins. I'm VERY partial to PING irons...just picked up the G2's and there is not a more forgiving club on the market (not just my opinion...I believe GolfWorld rated them #1 in latest survey). The best set I ever had were Ping Eye 2's...but were stolen out of my trunk. I've tried the Tommy Armours, the Cobras, the Titleist DCI's...nothing beats a ping iron in my opinion. I'd say go for the best club you can get...try the largest discounters you can find and ask for trade ins. I just traded in my DCI's for these and got all of $150...the salesperson said they'd probably just mark them up to $200-225. Great deal considering when they came out they were over $600.
Good luck--enjoy the game!