I don't have an example, but your bid will need to include:
1) Areas covered - What will we be cleaning?
2) Services covered (ie scope of work) - How will we be cleaning it?
3) Whether materials are covered or not - Is labor and materials included?
4) Price - How much will it cost. You can include pmt terms here too if applicable.
That's pretty much it for a simple bid. If you have a large, complex job, more detail is required (especially in the "scope of work" section). Other secondary details (ie what hours will we be working, etc) can be included in the contract after you've won the job.
site has some estimate samples for a construction business, but they can be easily modified to fit your needs.