The RC has rules for creating miscellaneous magic items on page 252.
According to these, a scroll would cost:
1,000gp x spell level (Initial Enchantment Cost) +
100gp x spell level (Single Charge)
With a 20% discount for being non-rechargable.
Therefore a scroll costs (880gp * spell level) to make.
It also needs a unique "special ingredient" that must be quested for rather than bought, and takes a week + a day per 1,000gp cost to make.
The chance of success is:
((Int or Wis + Level) x 2) - (3 x spell level)
If the roll fails, the money, time and special ingredient are all wasted.
Personally, I'd be tempted to skip the "Special Ingredient" for a scroll, or make it something not very special at all and therefore really easy to get hold of.
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