The type of hair loss you describe is quite common and is likely androgenic alopecia, which refers to female or male pattern baldness, and is hereditary. You might want to consult with a dermatologist, however, to rule out any other likely causes.
If it is indeed MPB, you are somewhat fortunate that it is only presenting in the crown, as medical therapies are typically most/only effective in this region. Propecia is a good first defense and works to treat hair loss in the vertex and anterior mid-scalp area. It should help you maintain your existing hair, and can even regrow hair in a small percentage of lucky individuals. Minoxidil/Rogaine is not quite as effective, from what I’ve seen, but many men feel more comfortable using a topical treatment and there are plenty who have seen satisfying results.
You are probably not a great candidate for a hair transplant at this point because of your age and because you should definitely try some of the medical therapies available to slow or stop your hair loss before making that leap. Hair transplants are not ideal for those who are experiencing thinning in the crown, as this region is somewhat of a ‘black hole’ for grafts (it requires more than anywhere else to achieve acceptable levels of density). Hair loss is progressive and your donor supply is limited so you would be wiser waiting to see if you will need to save grafts for your frontal hairline later on.
Disclaimer: I am not a physician. My opinions are not necessary those of Dr. Cole. My advice is not medical advice.