One of the players in our new Realms of Terrinoth game has alchemy. He would like to create dwarven firebombs and bottled lightning like Ulma (the dwarf pregen from the Haunted City) has. The cost and rarity of these are not in the RoT book. What is your opinion on what the cost and rarity might be? For reference, I’ve included the stats of these potions below.

Bottled Lightning - 7 Damage, Crit 5, Blast 7, Disorient 3, Limited Ammo 1, Stun Damage
Dwarven Firebomb -Damage 8, Crit 3, Blast 6, Burn 2, Limited Ammo 1

I'm looking at the Heavy Frag Grenade from EoTE Dangerous Covenants (Hired Guns) Sourcebook and it has a damage rating of 9, Blast 7, Crit 4, Rarity 5 for 75 credits. Though the damage is a little more that both of those you've listed, the extra qualities on those (Disorient 3 for the Bottled Lightning and Burn 2 for the Dwarven Firebomb) makes it about equal, in my opinion.

I think a Rarity of 6 (Hard difficulty to craft) and 75 credits or 70 credits (35 credits for materials if you want) would be more than reasonable or at least in the right ballpark for you.

Z

I have put them both at 75 moneys, with both at rarity 6 and the Firebomb restricted.

Thanks for the feedback!

$75 for buying it or brewing it yourself?

I asked the FFG about those a while back. The answer is posted in the FAQs thread, but (iirc) Sam gave the following values.

Bottled Lightning – Price 75; Rarity 6

Dwarven Firebomb – Price 200; Rarity 8