Price drops when more people buy

20% OFF Weekday Lunch Buffet - Mon to Thu
Snoball price
$9.60   20% OFF
Regular price  $12
Units sold this month  38
Units sold last month  NA
20% OFF Weekend Lunch Buffet - Fri to Sun
Snoball price
$10.40   20% OFF
Regular price  $13
Units sold this month  49
Units sold last month  NA
$10 Worth Coupon for only $8
Snoball price
$8   20% OFF
Regular price  $10
Units sold this month  18
Units sold last month  NA
$5 Worth Coupon for only $4
Snoball price
$4   20% OFF
Regular price  $5
Units sold this month  12
Units sold last month  NA