I would also recommend against using structure like single price, double price, triple price. I would use 2 fields Qty, Price. Assuming that double and triple prices were included to give a discount create a function that applies the discount. For example:
Single Price 20.00 each
Double Price 18.00 each
Triple Price 15.00 Each
Code:
Public function discount(ByRev price as currency, qty as long) as currency
Select Case qty
case is = 1
discount = price
Case is = 2
discount = price * .9
Case Is > 2
discount = price * .75
Case Else
discount = 0
end Select
The case else is there just in case there's a 0 or less qty