Highbeam said:
I was also going to suggest the 223 based on cheap ammo and effectiveness. It's not ideal for everything but does quite a nice job.
I have to agree on recommending a .223 for anything varmint and although I'm an outspoken advocate of the 5.56/.223 caliber, I have to disagree with you on the price. I'm ALWAYS hoarding/stocking up on 5.56/.223 ammo and I can definitely tell you that it's not cheaper than .17 ammo, no matter how you slice it!
I know you didn't say it was Highbeam, I'm just making my point
Military surplus, XM-193 is the cheapest quality ammo you can find on the internet. I'm still finding it occasionally for $380.00 per thousand and roughly 20.00 for shipping, or simply put, .40 cents per round. You have to shop around for it though. If you go with factory brand UMC, Remington, Winchester or Federal 50gr from Wallymart or any of the other brand name ammo, it'll cost you more than that.
Federal V-Shock, Hornady tipped 17grain - 17 caliber ammo will cost you about 14.00 with tax at Wallymart for 50 rounds. Simply put, about .28 cents per round. You won't find .28 cents a round 223 ammo anywhere that's worth a hoot, and if you do, it'll be Wolf. I'm not a Wolf ammo fan, I've seen too many jams, misfires and double-feeds with it, steel cased, brass moly or whatever.
My .28 cents worth...
Podunk