pennisiside, Yes they are $6.00 each for a 50lb block and they will last between 8-12 months before you have to replace them.
As far as where to get them any feed store should carry them.
crockit, my property is in OH. so I leave them out 12 months a year, in PA. you have to remove any mineral blocks, licks etc. and the dirt around them atleast 30 days prior to the season, or you or anyone else for that matter cannot hunt within I think its 500 yards of the site. (always removed them prior to the season in PA. so im not 100% sure of the distance) Pike