What kind of sealant was last used on the home?
Do you need to strip it?
I use a percarbonate base cleaner and brighten with oxalic acid. Let your chemicals do the work - it will fur on you - use minimum pressure. Then I seal with Ready Seal.
If you need to strip - I use a light dose of hd80 (as light as possible).
The key is to allow your chemical enough time work before starting to wash.
As of bid - I normally bid by square foot - clean, brighten, & seal = approx. $1.25 sqft...... Stip, brighten, & seal = $1.75
There are a lot of other factors to consider: one or two story, possible rental of equipment, condition of wood, type of sealant currently on the home, etc.
I rigged up a device for appying chemicals - I bought a 18 foot (retractable) painters pole, taped my sprayer to the end & the hose along the pole, the hose is attach to a sur flow pump and 5gal bucket. I can spray chemical and sealant from the ground - much faster than ladder or platforms. You have to use a sealant that will not leave lap marks, like Ready Seal. I do a lot log homes this way.