What are the requirements and the costs for a Dubai real estate visa for 3 years??

There are two different visas, a 3 years visa and a 5 years visa.

3 years visa: Requirements & fees.

A copy of the title deed.
A copy of the passport with the country entry stamp.
A certificate of good conduct from the General Department of Criminal Investigation (it may be submitted through the Dubai Police website if an ID card is available).
If the property is mortgaged, a No Objection Certificate (in Arabic) can be utilized to issue a residence permit on a property from the bank, accompanied by a sealed statement of the mortgage account.
Fees amount to AED 16,000 every three years.