I'd like to make an underground base, but I don't want to spend a lot of time or money on it. I have access to divine spells and psionic powers, and whatever magic item creation feats are needed.
My priorities, in order, are:
- Cost. I'd much prefer options that don't cost any money, and especially options that only involve spells, or reusable magic items. If it will cost more than 30k gp or so, it's too expensive for me.
- Time. I'd prefer faster options to slower ones. I'd prefer options that take fewer spells, so I can do them more times in a day.
- Versatility. It would be helpful if there were walls and supports included in the plan, in case I need a base in an area that's mostly dirt, instead of stone. Similarly, having a way to avoid using wall of stone, which requires existing stone to use, would be great. Also, solutions that work at lower levels are much better than ones that require high levels. I would much prefer solutions that need no more than 6th level spells.
- Low play time cost. I'd prefer solutions that didn't require a lot of time spent in play to do. Anything that would take an adventure on its own to accomplish, or would require exploring the world more is less helpful.
- No use of arcane spells. In my current game, we don't have a full arcane caster, so I'd prefer options that only use divine or psionic spells.
- Comfort. If there's a way to create doors, stairs, and other furnishings while making the base, that would be better than not.
Basically, of the "good, fast, cheap, pick two", I'd pick cheap and fast first.
Note that this doesn't necessarily need to involve spellcasting, I just assume that spellcasting will be the most efficient way to do this.
Answers should say how much underground area the approach can create, and how much is costs per unit area. For example, making rooms using disintegrate and wall of stone costs 1 6th level spell and 2 5th level spells per 10X10X10 cube, or 1 5th level spell at level 12 or higher.
Feel free to ask more questions, in case there's something that I'm not including.