[RPG] How much does a corpse cost

You're looking for Magnimar, which is a Large city located roughly 50 miles south of Sandpoint.

You've asked: "Are there any other avenues to bring someone back from the dead?" Common avenues include:

• the reincarnate spell, which is cheaper and lower-level, but can alter your physical stats
• the breath of life spell, which only works if you cast it within one round of death -- consider buying a scroll and giving it to your divine caster, just in case
• the first aid gloves, which cost 4500gp but can cast breath of life twice, usable by any character

No, constructs are not mundane alchemical items:

you may create mundane alchemical items much more quickly than normal.

They are creatures. Mundane alchemical items would be Acid Flask, Alchemist Fire, Tanglefoot Bags, Sunrods and several other alchemical items.

The benefits of Promethean Disciple is to allow alchemists, who are normally not spellcasters (see this FAQ) to craft constructs, which requires levels on a spellcaster class:

Prerequisites: Caster level 5th, Craft Magic Arms and Armor, Craft Wondrous Item.

And this last part that should reduce the time spent creating a construct does not apply at all, as they use a different rule for crafting them (see magical item creation) that is already much faster than mundane crafting.

In addition, whenever you make alchemical items or poisons using Craft (alchemy), use the item’s gp value as its sp value when determining your progress (do not multiply the item’s gp cost by 10 to determine its sp cost).