It's not unusual. If you are not comfortable tell them you are willing to do 50% upon delivery of materials, balance upon completion.
Each contractor's license issued in the State of Nevada requires a license bond. The Nevada State Contractors Board determines the amount of the bond at the time of license approval. The bond can vary in amount from $1,000 to $500,000.
How to draft a contract between two parties: A step-by-step checklist Know your parties. Agree on the terms. Set clear boundaries. Spell out the consequences. Specify how you will resolve disputes. Cover confidentiality. Check the legality of the contract. Open it up to negotiation.