Frequent buyer's club

Yes, it does exist.  Some thrift stores have started frequent buyers club where the amount you purchase gives you a discount off future purchases.

For now, there are few that I do remember.  The Central Okanagan Salvation Army which has 3 branches has a neat program where you earn points per dollar spent, a generous 10 points per dollar (fractions count - essentially 1 point for each 10 cents spent) and each point is worth 1 cent, redeemable in increments of 500 points ($5).  If you quote the phrase of the week, published on the facebook page, you get an extra 25 points with a minimum $5 purchase once a day.

The North Okanagan (Vernon) Salvation Army has a similar program for its 2 shops.

The MCC in Rutland use a punch card program where you get punches on a card for a certain minimum (I think it is $5).  Have a filled card and you get a discount.

The Salvation Armies of Nanaimo and of the Comox Valley also use a punch card.  Minimum purchase applies ($10/punch for Comox Valley).