Shawn - Builders cleans are a nightmare if not priced properly I know from experience.
The windows alone on a 3 bed semi seem to take forever as they are normally covered in mortar.
Then floors to scrape , surrounds of windows, all paintwork.
I underpriced for ages thinking it would not take that long and wished I had never quoted.
3 bed Semi minimum £300 depending on the state of it.
We did a 20 bed care home recently, floors,windows in/out,paintwork,radiators,bathrooms,fixtures +fittings I quoted £3,200 I thought it was a high price at the time but it was not then to rub salt into the wounds I found out off the foreman that the next quote up was £7,500.
We did a great job and are now doing alot more work for the same company but at higher prices so the low price got me in there to show your worth then to charge higher.
There is a contract going up for grabs from julianbiggs on this forum for a £10,000 contract to clean 25 houses 4 times but after working it out it works out at £100 per clean. (4 cleans per house x 25 houses.
Just be careful because it does get you down if it turns out poor.
In my eyes you pay for what you get.
Good luck Robbie - Clearshine - Harrogate