Honestly the best place{cheapest} to buy a ruger 10/22 is from wal-mart. you can get a base model 10/22 for $198+tax. if you're just looking for a standard carbine I wouldnt pay more than $220 out the door. depending on you size the carbine may be to short for you..Im 6'4" and 220# and the carbine is way to short for me,I've found that the 10/22 sporter deluxe is a good fit for me but they do run a little more,on average they cost about $275.
I really enjoyed the appleseed events I attended..they are alot of fun and helped me tremendously! a few mods that you may be interested in doing to the 10/22 to help you during an appleseed is an auto bolt release mod,which can be done with a dremel tool or you can buy a new plate for about $12 and the other mod would be an extended magazine release..the extended release will save you ALOT of headaches when on the line. this can be done for as little a couple of dollars for a home made one or as much as $40 for the more fancier parts.
also..if you're not to keen on purchasing a firearm from wal-mart{I know some people aren't} you may want to check out budsgunshop.com their prices are comparable.
hope this helps and if ya have any more questions feel free to ask.