I am 25. Could you tell me the rough estimate of grafts I require and total expenses for transplantation, please? (Photo)

The number of grafts you need depend on how much more hair you will lose as well as your goals and expectations.  Some may be happy with 1000 grafts while others may need 2000 grafts.  The cost of surgery can vary from low thousands of dollars to well over 10,000 dollars USD based on where, who, and what type of surgery you have.

You are a very young patient with temporal hair loss and thinning.  The most important first consideration is your family history and an estimate as to how much hair you may lose in the future.  The next step is to do everything possible to slow down your hair loss.  For male pattern baldness, minoxidil 5% and finasteride are both recommended if tolerated.  I also strongly recommend cellular therapy such as SVF and PRP.   PRP has been shown to slow the progression of hair loss and stimulate dormant follicles.  Once you lose hair in the temporal area (i.e. there are no vellum or baby hairs remaining), transplant is generally indicated.  It is always very difficult to make estimates based on photos such as yours because the scale can be distorted.  In general a density of about 40 FUE/cm2 is recommended.  You look like you have about 30 cm2 of area requiring transplant, so that equals about 1200 grafts.  Depending on the skill of the surgeon, FUE generally costs in US dollars about $6 to $10 per graft.   I recommend you combine cellular therapy with FUE for the best result.  For more information about this technique follow the link below. 

You have a Class 3A pattern of balding. Costs are usually calculated as the cost per graft so if you look at our gallery (see below in web reference) you can pick out someone like you and see how many grafts that had done to get the results shown. A Class 3A pattern with normal hair weight (not fine hair) will usually take about 2000 grafts to get a reasonable result. So, if the cost per graft is $5, then 2000 grafts would cost you about $10,000. The quality and the experience of the team is critical to get the results you expect. Again, go through the gallery below. 

I determine the amount of hair grafts needed by measuring the area of the recipient area.  In a recipient  area devoid of any hair, I strive for 350 hairs per square inch.  Roughly,  I measured 6 square inches on your frontal hairline.  That comes to 2100 grafts, mostly one hair grafts.