I originally posted this over in the real estate forum, but it was recommended that I ask here.

As I shop for a house, I'm considering some that have pools and spas. I've read extensively about the pros and cons of pools and spas, so that's not what I'm asking about here.
What I want to know is the best way to estimate how much I should expect to spend on keeping a pool and/or spa going:

Pool maintenance person
Heating
Power for the pump
Water consumption
What else?

I know this can have huge variation, but without having any idea, it makes it very hard to create a budget and figure out how much house I can comfortably afford. I've seen some people claim that their entire expense is under $100/mo, and others claiming over $1k/mo. That has a massive impact on affordability. In general I'm plugging in "worst case scenario" numbers into my budget, so any surprises are for the better rather than the worse. But with a range this wide, it starts to get ridiculous.

Someone told me to ask the seller for utility bills. That's fine, once we get to the offer stage, but when I'm considering 3 dozen possible places, half of which have a pool or a spa, it's not really practical.

Can anyone give me some help here? Resources I can look at? Guidelines to use? I'm in Southern California.

Pool Size - Larger pools require more pump time and more chemicals. The cost is pretty linear with volume so just figure a pool the twice size is going to cost twice as much to operate, assuming everything else is the same.

Pump Size - Large HP pumps use more energy per gallon of water pumped. Two speeds and variable speeds are much more efficient and can cut energy costs in half. If the houses you are looking at have pools with large single speed pumps, figure that you will need to replace at least the motor to get some efficiency.

Heating - Heating any pool can be expensive if you are using gas or electricity. However passive solar panels can be a very inexpensive way to reduce costs.

Solar Cover - Prevents heat loss through evaporation so it saves both water and heat costs. A pool with an autocover can be a real cost saver.

Pool Maintenance - DIY, it really isn't that hard plus most pool services really don't know what they are doing.

But in general, you can make almost any pool more energy efficient. It takes a little knowledge and sometimes extra money.

I am in No CA and have put some effort into minimizing costs so here are some of my stats:

Pool Size: 20k gallons
Pump Size: 1/2 HP 2 Speed Pump
Heat: EPDM Solar Panels
Chlorinator: SWG
Solar Cover: Most of the summer
Summer run time: 1 Turnover per day (120 kwh/month)
Winter run time: 1/2 Turnover per day (60 kwh/month)

Below is a link for evaporation rates for unheated pan tests. This would be the minimum loss without a cover and without additional heat. For me, it is 60" per year which equates to 2750 cu-ft and our water rate is around $2/100 cu-ft so about $54/year. Halve that if you are using a cover half the time and double it if you don't use a cover AND have solar. But for most pools, the pump and heating energy cost will well exceed the water cost.