In a thread on the Paizo forums someone asked a question about scroll costs, and what are some of the best scrolls to scribe versus not scribing; and communal scrolls were mentioned. However another poster threw out the figure of a (x6) scroll cost for communal scrolls. Is this legitimate? Where does this figure come from?
The cost of scribing a scroll is always
12.5 gp × the level of the spell × the level of the caster. (Core, p552).
Whether the spell is Communal or not does not matter, except in that a communal spell is usually one level higher.
I imagine that the person was talking about a specific spell. The spells ant haul (Advanced Player's Guide p202), endure elements(Core p277), mask dwemer (Advanced Player's Guide p232), mount (Core p315), protection from chaos/energy/evil/good/law (Core p327), reinforce armaments (UC p212), returning weapon (UC p214) are all spell level 1 (for at least one class), and have a communal version in Ultimate Combat that is spell level 2.
The regular version of each of those spells have caster level 1 as a minimum, so their scrolls would have a minimum cost to scribe of:
12.5gp × 1 × 1 = 12.5gp
The communal version of each has a minimum caster level of 3. Since the spell is second level, the communal version would have a minimum cost to scribe of
12.5gp × 2 × 3 = 75gp
Which is 6 times the cost of the spell level 1 version. Worth noting is that if the scroll for the regular version is made at a caster level other than 1, or if the difference was not between spell levels 1 and 2, the other poster stops being correct.