Surprisingly due to popularity the 223 is actually not cheaper and in some cases more expensive then 22-250 ammo. But if you do use surplus ammo then .223 will deffinately be cheaper then 22-250 ammo. The only problem with surplus ammo is you will be limited to FMJ's and sometimes match hollow point ammo, match hollow point ammo is not designed to expand so i really wouldnt recommend it for use on game.

I had actually gone through the same problem trying to decided between .223 and 22-250 for a varmint gun, as a handloader i decided on a 22-250 because of the versatility of the 22-250. I can load up to 22-250 velocities or tone them down to 223 velocities depending what bullet im wanting to push. Either is a good choice, what you have to do is think about what exactly you want to do and weigh the pro's and con's of each caliber and see which one suite your fancy the best. good luck